Category Archives: Pollinators

Biting Insects, Medical Entomology, Pollinators

Do mosquito yard sprays harm other insects?

If you’ve noticed all the lawn signs for mosquito treatments, you may be wondering if mosquito yard sprays harm other insects. If so, you’re not alone.  As an Extension entomologist, this is a common question that I get from the public every year.  To get to the bottom of this question, it helps to understand the different types of mosquito spraying that’s done.

One approach (Ultra Low Volume or ULV) is sometimes used by municipalities or abatement districts to control mosquitoes.  These ULV applications generally involve using specialized equipment mounted on trucks or aircraft to apply extremely tiny droplets which kill adult mosquitoes by direct contact as the droplets float in the air.  Such applications use very small volumes of insecticides either undiluted or with minimal dilution and are often applied after dark when mosquitoes are most active.  The microscopic droplets from ULV treatments disperse relatively quickly and have little residual activity—think of them like a “one time strike” to knock down mosquito numbers.

The vast majority of research on mosquito sprays and non-target organisms has looked at these ULV-type treatments.  Some good news is that these studies suggest that impacts to non-target insects are relatively small and short-lived.  It turns out that the ULV treatments are most effective on insects with very small body mass, so insects larger than mosquitoes tend to be spared.  A good summary of the impacts of ULV treatments on non-target organisms can be found in a 2012 review paper by J.A.S. Bonds in Medical and Veterinary Entomology. 

Many mosquitoes like to rest on vegetation during the day, so some mosquito sprays specifically target these resting sites. Photo credit: Public Domain Image.

Case closed, right?—Not quite. Here in Wisconsin, we don’t really use ULV treatments a whole lot for mosquitoes.  The common yard treatments are what we’d call “perimeter”, “barrier”, or “residual” treatments.  Such treatments are applied via a backpack sprayer to create a coating or “barrier” on treated surfaces which affects mosquitoes that land on it.  These treatments involve applying a residual insecticide (usually from the pyrethroid group) to vegetation in yards and around structures.  The pyrethroid products are broad-spectrum and often last for a few weeks or longer depending on the formulation.  These same ingredients (and sometimes the exact same products) can also be used to control a wide range of yard, garden, and structural pests (e.g., Japanese beetles, garden pests, household ants, etc.).

While the pyrethroids are very common and widely used for a range of purposes, there’s a knowledge gap when it comes to the impacts of mosquito “barrier” treatments on other insects.  While this knowledge gap exists, a few studies raise concerns.  One study by Dr. Karen Oberhauser and colleagues found that monarch caterpillars could be harmed or killed even 3 weeks after spraying.  A more recent (2022) study by Qualls et al. found that honey bees were harmed 28 days after “barrier” treatments were applied.  Thus, if a yard is being sprayed for mosquitoes monthly during the warm season, there are reasons for concern.  More research is needed to help understand the effects of these “barrier” yard treatments on insects that often land on vegetation in yards, such as moths, butterflies, fireflies and other beetles, true flies, bees, wasps and other pollinators.  

Fireflies can be very common on vegetation in a yard during the summer months. Scientists view pesticides as a concern for fireflies globally. Photo credit: RachelEllen via FLickr CC.   

References:

  • Bonds, J.A.S. 2012. Ultra-low-volume space sprays in mosquito control: a critical review. Medical and Veterinary Entomology. 26: 121-130. 
  • Oberhauser, K.S., Brinda, S.J., Weaver, S., Moon, R.D., Manweiler, S.A., and N. Read. 2006. Growth and Survival of Monarch Butterflies (Lepidoptera: Danaidae) After Exposure to Permethrin Barrier Treatments. Environ. Entomol. 35(6): 1626-1634.
  • Qualls, W.A., Moser, B.A., Periera, R.M., Xue, R-D, and P.G. Koehler. 2022. Impacts Of Barrier Insecticide Mixtures On Mosquito, Aedes Aegypti And Non-Target Honey Bee, Apis Mellifera.  Journal of the Florida Mosquito Control Association 69: 34-42.

 

 

Bees, Pollinators, Wasps and Bees

In Defense of Ground Bees

“Ground bee” season is officially here, but before we get any further, let’s clear up a few things about these insects.  Ground-nesting bees get a lot of undeserved blame for stings that they simply aren’t responsible for.  Despite their claims, many folks have probably never been stung by an actual “ground bee”.  Every year I get plenty of calls about “angry stinging ground bees” in late summer, but these are almost always ground-nesting yellowjackets (Vespula spp.).  Undoubtedly, if you stumble into an in-ground yellowjacket nest, you’ll be forced to make a hasty retreat from the area as the colony defends itself.  But those aren’t bees…

Entrance of a ground-nesting yellowjacket nest in late summer. These might be black and yellow, but they aren’t bees… Photo credit: Jeff Hahn, U. Minnesota.

While yellowjackets and bees are related (both belong to the insect order Hymenoptera along with the ants and sawflies), they belong to completely different families.  From a standpoint of taxonomic classification,  mixing up yellowjackets and bees would be like confusing dogs for cats, raccoons, or walruses (all belong to separate families within the mammalian order Carnivora).  We do technically have social, ground-nesting bees that can be ornery if disturbed (i.e., bumble bees), but folks generally recognize bumble bees by their large size and robust appearance.  

A solitary ground nesting bee guarding the entrance to its nest in a city park in Middleton, WI. Photo credit: PJ Liesch, UW Entomology.

So what about these other “ground bees”?  Most bees (about 2/3 of all bees) are actually ground-nesting species.  In the Midwest, we’ve got around 500 different bee species, meaning there are hundreds of ground-nesting species around us.  Our common ground-nesting bees include species of: cellophane bees, mining bees, squash bees, longhorned bees, sweat bees, and others. For the most part, these ground-nesting bees are solitary creatures that live alone, although many nests can occur in the same general area as shown in the video clip below.  They often prefer sunny, open areas with thin ground cover or bare, sandy soil and can be common in parks and home lawns.  

To a certain extent, solitary bees can be thought of as the insect equivalent of “preppers”.  Each bee digs her own nest—a small, bunker-like tunnel in the ground, which looks like an ant hill.  Not only do the females have to construct these shelters, but she has to gather all of the provisions needed for her young to survive inside—often in the matter of just a few weeks.  The female bees collect pollen and nectar from flowers to create a nutritious substance called bee bread, which they place into small chambers (cells) and lay an egg.  Once the eggs hatch, the young bees (larvae) have all the supplies they’ll need to grow and develop in their survival bunkers.  

Most of these ground bees have a single generation per year.  The adult bees are out and active for a short period of time (often a few weeks), before they’re done and gone for the year.  When they are active, our solitary bees can be excellent pollinators and can be more efficient than honey bees in some regards.  However, their pollination services often go unrecognized and unappreciated by the general public.  While news articles regularly sound the alarm about honey bee declines, we should really be much more concerned about the potential loss of our solitary bee species, as they’re more sensitive to disturbances, pesticides, and other stressors.

Post-jog entomologist next to five solitary bee nests. These bees are extremely gentle and unlikely to sting. This portion of a local park had thousands of solitary bees flying around. Photo credit: PJ Liesch, UW Entomology.

If you spot ground bees this time of the year, is there any reason for concern? No. Solitary ground-nesting bees are great to have around.  Being solitary nesters, these ground bees don’t have a large colony of  adult relatives to defend and they end up being surprisingly gentle and unlikely to sting.  Overall, they pose little risk to people or pets.  The best thing to do is to simply let them be and appreciate the pollination services they provide. 

If you’d like to learn more about Wisconsin’s bees, check on the Wisconsin Bee Identification Guide or the US Forest Service’s Bee Basics: An Introduction to Our Native Bees. If you have solitary ground-nesting bees in your yard and would like to teach others about these amazing pollinators,  click the image below to get a  sign to laminate and post:

A yard sign about wild bees

IDL Highlights, In the News, Pollinators, Wasps and Bees

Great Golden Digger Wasp: Another Asian Giant Hornet Look-Alike

With the media craze about “murder hornets” this past spring, I’ve seen a definite increase in reports of Asian giant hornet look-alikes at the UW Insect Diagnostic Lab this summer.  Many folks recognize the commonest look-alike in the Midwest, the eastern cicada killer (Sphecius speciosus), which becomes active in July around the time that their prey (cicadas) start emerging.  Another look-alike is one that you might not have bumped into before—the great golden digger wasp (Sphex ichneumoneus).  Similar to Asian giant hornets, great golden digger wasps are large and nest in the ground, which are reasons why they may be mistaken for the former.

If you haven’t spotted one before, great golden digger wasps can be a bit intimidating in appearance as they can easily be over an inch long.  However, their anatomy and appearance are quite different compared to Asian giant hornets.  Great golden digger wasps are mostly black with a rusty-reddish color at the base of the gaster (“abdomen”).  Their legs are the same reddish color and the black thorax and head possess fine golden setae or “hairs” (hence “golden” in their name).  In contrast, Asian giant hornets have distinctive black and yellow stripes on their gaster and a vibrant yellowish-orange head.  Great golden digger wasps belong to the “thread-waisted” wasp family (Family Sphecidae) and have a long, slender petiole (“waist”).  This isn’t as thin and narrow as the “waist” of the related black and yellow mud dauber (Sceliphron caementarium), but still is quite noticeable when viewed from the side.

Great golden digger wasp
Great golden digger wasp (Sphex ichneumoneus); note the slender petiole or “waist”. Photo credit: Judy Gallagher, via Wikipedia.

In terms of their biology, both Asian giant hornets and great golden digger wasps do nest in the ground, but the similarities end there.  The Asian giant hornet is really quite similar to our ground-nesting yellowjackets in terms of their nesting behavior.  These are social creatures which start nests from scratch in spring and build up in size over the course of the warmer months.  Colonies ultimately die out in fall except for the “new” queens which overwinter.  With a large colony of relatives to defend, social wasps can be defensive, especially when colonies are at peak size.

In contrast, great golden digger wasps are solitary ground nesters.  Without a large colony of relatives to defend, they’re usually non-aggressive and very unlikely to sting.  Stings are only likely if one were to pick one up bare-handed—in which case you might be asking for it!  Similar to cicada killer wasps, each female great golden digger wasps excavates small tunnels in sandy soil and provisions them with prey for their young to feed on.  In the case of the great golden digger wasp, prey consists of katydids, crickets, and relatives from the “grasshopper” group (Order Orthoptera).  Rather than kill outright, the females inject their prey with a paralytic “cocktail” to keep them alive and fresh for their young to feed on—what a way to go!  In addition to hunting katydids, adult great golden digger wasps visit flowers and can be beneficial pollinators.

Great golden digger wasp on flower
Great golden digger wasp (Sphex ichneumoneus) drinking nectar from a flower. Photo credit: Roy Niswanger, via Flickr.

Because they’re unlikely to sting humans, controlling great golden digger wasps is rarely justified and these magnificent creatures can simply be admired.  Ultimately, these wasps are strongly associated with sandy soil, so if you see them in your yard every year and would prefer to not have them around, modifying the landscaping may be a long-term option to dissuade them from an area.

Author’s note: As of August 2020, Asian giant hornets have not been found in Wisconsin or anywhere in the Midwest.  In North America, these insects are only known from far northwestern Washington state and nearby parts of British Columbia. 

See this earlier post for additional details on the Asian giant hornet.

Butterflies, Pollinators

5 Spring Butterflies to Brighten Your Day

Does the COVID-19 situation have you cooped up at home? If so, you’re not alone during these unusual times. With the shift towards working from home, folks are spending more time in their own yards and gardens as well as nearby parks and nature trails. Spending time out in nature can have notable health benefits, but it also gives us a great opportunity to observe the creatures around us—including insects, such as butterflies.

In Wisconsin and the Upper Midwest, summer may be “peak” butterfly season, but a number of species can be active early in the year.  These creatures might brighten your day during these tough times, and this guide will help you identify five of the commonest spring butterfly species in the Upper Midwest:

Mourning Cloak (Nymphalis antiopa):
This butterfly is often the first one seen in spring. It’s an easy species to identify given its large size (3-4 inch wingspan) and colors on the upper wing surface—dark wings bordered with a row of small blue spots and pale edges. Mourning cloaks overwinter as adult butterflies amongst leaf litter or in other sheltered spots, so as soon as it’s warm enough they can become active. This butterfly can catch people off guard if they fly while snow remains on the ground. In early spring when flowers haven’t bloomed yet, mourning cloak butterflies are fond of visiting the sap flows on trees caused by the activity of the yellow-bellied sapsucker.

Mourning Cloak Butterfly
The mourning cloak butterfly (Nymphalis antiopa). Photo credit: Mike Lewinski via Flickr.

Eastern Comma (Polygonia comma):
Like the mourning cloak, eastern commas overwinter as adult butterflies, so they’re ready to go as temperatures creep upwards. Eastern commas have a wingspan of approximately 2 inches. When spread, the wings are mostly orange with black spots and borders.  The edges of the wings also have a “wavy” or “scalloped” appearance. The most distinguishing feature can be seen on the undersides of the wings when folded upwards: a small pale curved mark in the shape of a comma—hence the name. The closely-related question mark (Polygonia interrogationis) can also become active fairly early in the season and looks similar, but has a “?” shape on the underside of the hindwings.

Eastern Comma Butterfly
The eastern comma butterfly (Polygonia comma). Photo Credit: Matt Tillett via Flickr.
Eastern Comma Butterfly-Underside
The eastern comma butterfly (Polygonia comma) displaying the distinctive white “comma” marking on the underside of its wings. Photo credit: Ryan Kaldari via Flickr.

Red Admiral (Vanessa atalanta):
The monarch butterfly (Danaus plexippus) is perhaps the best known migratory insect in our part of the world, but red admiral butterflies also migrate northwards in spring. The migratory behavior means that the arrival date and numbers can vary greatly from year to year, but red admirals can frequently be encountered in spring in the Upper Midwest. These butterflies have a wingspan of approximately 2 inches and have black wings with prominent white “!” marks near the tips of their forewings and a distinctive reddish-orange band cutting across the surface of their forewings.

Red Admiral Butterfly
The red admiral butterfly (Vanessa atalanta). Photo credit: Kenneth Dwain Harrelson via Wikipedia.

Cabbage White (Pieris rapae):
Right around the start of the Civil War, the cabbage white made its first appearance in North America. Today, this European butterfly can be found widely distributed across much of the planet. Cabbage whites are indeed a whitish color with sooty black patches at the tips of their forewings. The forewings also possess black spots—1 spot for males, 2 for females. Their pale appearance and decent size (approximately 1 ¾ inch wingspan) make them easy to identify this time of the year.

Cabbage whites overwinter as chrysalises in the Upper Midwest, so they aren’t active quite as early as the mourning cloaks or eastern comma. However, the warmth of the sun can still lead to early spring sightings. Gardeners and vegetable farmers are well aware of this species since the caterpillars (“imported cabbageworms”) feed on plants from the mustard family—including broccoli, cabbage, and Brussels sprouts.

Cabbage White Butterfly
A cabbage white butterfly (Pieris rapae). Photo credit: Andy Reago & Chrissy McClarren via Flickr.

Spring Azure (Celastrina ladon ladon):
If you spot a cluster of small bluish butterflies around a puddle on a hiking trail in spring, there’s a good chance they’re spring azures. These butterflies are the smallest on this list, with a wingspan of only around 1 inch. The beautiful sky blue color of their wings can be seen in flight, but when they land, spring azures tend to keep their wings folded over their body, showing the grey undersides with an assortment of tiny black mark. There are many other species of small blue butterflies in our area throughout the year, but the spring azures are some of the earliest to fly and are wrapping things up for the year as June approaches.

Spring Azure At Rest
A spring azure butterfly (Celastrina ladon) at rest showing the undersides of the wings. Photo credit: Anita Gould via Flickr.
Spring Azure Butterfly
The beautiful blue spring azure butterfly (Celastrina ladon). Photo credit: Seabrooke Leckie via Flickr.

The Upper Midwest is home to over 150 butterfly species—each unique in its appearance, biology, and distribution. If you’re looking for some additional resources to learn about our butterflies, some of my favorites include: Butterflies of the Northwoods by Larry Weber, A Swift Guide to Butterflies of North America by Jeffrey Glassberg, and the Wisconsin Butterflies website (wisconsinbutterflies.org) by photographer Mike Reese. The Wisconsin Butterflies website not only has wonderful photos and a wealth of information about each species, but users can view and submit butterfly sightings from around Wisconsin.

Butterflies, Caterpillars, Crop Pests, Medical Entomology, Moths, Ornamental Pest, Pollinators, Sawflies, Shrubs

2018’s Top Trends from the Diagnostic Lab (Part 2)

In this post, we’re continuing to count down the University of Wisconsin Insect Diagnostic Lab’s top arthropod trends of 2018. This is the second half of a two part series; the first half can be found here.

5) White-Lined and Other Sphinx Moths:
The white-lined sphinx moth (Hyles lineata) can be a common species, so encountering one of the 3 inch long hornworm caterpillars isn’t unusual. However, these caterpillars can also be encountered in massive road-traversing hordes if the conditions are just right. From midsummer onwards, large numbers of these caterpillars were observed around the state—in some cases by the tens of thousands. If you didn’t spot any of the caterpillars themselves, you might have encountered the large adult moths with their hummingbird-like behaviour in late summer. Several other sphinx moths species also had a strong presence in 2018, such as the clearwing hummingbird moths and the tobacco and tomato hornworm caterpillars which can regularly be encountered in gardens as they munch away on tomato and pepper plants.

Large, dark-colored hornworm caterpillar of the white-lined sphinx moth on a plant
Large, dark-colored hornworm caterpillar of the white-lined sphinx moth. Photo submitted by Ted Bay, UW-Extension

4) Sawflies:
Sawflies, the caterpillar copycats of the insect world, are a diverse group, so they’re always present to some extent. Last year saw an unexpected abundance of two particular types in Wisconsin—the dogwood sawfly and the non-native Monostegia abdominalis, which feeds on creeping Jenny and related plants from the loosestrife group (Lysimachia species). While sawflies are plant feeders, dogwood sawflies can also damage the soft wood of a home’s siding or trim when these insects excavate small chambers to pupate in. The UW Insect Diagnostic Lab saw a distinct bump in reports of wood damage from the dogwood sawfly last year.

Whitish larva of the dogwood sawfly curled up on a dogwood leaf
Larva of a dogwood sawfly showing the whitish, waxy coating. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

3) Armyworms:
True armyworms (Mythimna unipuncta) can be a dynamic and sporadic pest in the Midwest. This species doesn’t survive the cold winters of our area, so adult armyworm moths must invade from the south each spring. Depending on national weather patterns, the arrival of the adult moths can vary significantly from year to year. If an early mass arrival is followed by abundant food and ideal conditions for the ensuing caterpillars, large populations can result. Once they’ve arrived, true armyworms can go through 2-3 generations in the state and this second generation of caterpillars made an alarming appearance in mid-to-late July. Under the conditions last summer, massive hordes of these caterpillars decimated crop fields before marching across roads by the tens or hundreds of thousands to look for their next meal. In some cases, that next meal included turfgrass, meaning that some Wisconsinites came home from work to biblical hordes of caterpillars and half-eaten lawns in late July.

Striped caterpillar of the true armyworm
Caterpillar of the True Armyworm (Mythimna unipuncta). Photo Credit: Lyssa Seefeldt, University of Wisconsin-Madison Extension

2) Monarch Butterflies:
Much to the delight of fans and conservationists, the iconic monarch butterfly (Danaus plexippus) appeared to have a banner year in the Midwest in 2018. Reports and observations of high numbers of monarchs poured into the Insect Diagnostic Lab during the summer months. As comforting as these reports were, the butterflies still faced a perilous 2,000 mile journey to reach their overwintering grounds in Mexico.  The most consistent measurement of the eastern monarch population comes from estimating the area occupied by the densely-packed overwintering butterflies.  In late January the latest count was released with encouraging news—the eastern monarch population is up 144% over last year and is estimated to be the largest in over a decade.  In contrast, the western monarch population overwinters in southern California and has recently dipped to alarmingly low numbers. Regardless of the winter assessments, monarchs face tough challenges and Wisconsinites are encouraged to help conserve this iconic species.  The Wisconsin Monarch Collaborative recently launched a website with resources for those wishing to join the effort.

Seven monarch butterflies nectaring on a flower
Multiple monarch butterflies nectaring on a single plant in August. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

1) Floodwater Mosquitoes:
Mosquitoes snagged the top spot on 2018’s list for good reason. The upper Great Lakes region is home to over 60 different mosquito species, but one subset—the “floodwater” mosquitoes—drove the storyline last year and impacted outdoor activities through much of the spring and summer months. Mosquitoes in this group, such as the inland floodwater mosquito (Aedes vexans), flourish when heavy rains come. Last year’s mosquito season kicked off in force with a batch of pesky and persistent floodwater mosquitoes just before Memorial Day weekend. Mosquito monitoring traps in southern Wisconsin captured record numbers of mosquitoes shortly thereafter. Later in the year, the Midwest experienced an unprecedented series of severe rainstorms, setting the stage for an encore performance of these mosquitoes. It was this second explosion of mosquitoes that caught the attention of anyone trying to enjoy the outdoors in late summer—a time of the year when mosquitoes are typically winding down in the state.

Ephemeral pools of water created ideal conditions for floodwater mosquitoes in late summer. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab
Big Bugs, Moths, Outdoor Worms, Pollinators

Sphinx Moths—Hovering at a Flower Near You

If you’ve watched the flowers in your yard or local park recently, you might have noticed some surprising visitors hovering at the flowers—the hummingbird-like sphinx moths.  Several species in the “sphinx” or “hawk” moth group (Family Sphingidae) are known for their day-flying, hummingbird-like behavior.  From a distance these moths can easily be mistaken for hummingbirds as they skillfully maneuver from flower-to-flower sipping nectar with their long mouthparts.

One of the commonest members of this group in Wisconsin is the white lined sphinx moth (Hyles lineata).  With a wingspan of nearly 4 inches, it’s easy to understand why this species can be mistaken for a hummingbird as it feeds.  The greyish adults are easy to pick out and a white stripe on each forewing helps identify them in the field.  The caterpillars (hornworms) of this species reach nearly 3 inches in length and can feed on a wide range of plants.  While this species is regularly encountered in the Midwest, this year has been especially good for white-lined sphinx moths in Wisconsin.  In mid-to-late July I received many reports of the caterpillars—sometimes in astounding numbers.  In several instances, “outbreaks” of tens of thousands of these large caterpillars were spotted as they migrated across roadways from agricultural fields.  The multitudes of caterpillars have since pupated and transformed into nectar-loving moths—leading to a recent spike of sightings.

White-lined sphinx moth (Hyles lineata). Photo Credit: Andy Reago & Chrissy McClarren; Wikipedia

In addition to the white-lined sphinx moth, several other hummingbird-like sphinx moths have been common this year—the “clearwing” hummingbird moths (Hemaris spp.) and the Nessus sphinx moth (Amphion floridensis).

The rusty-colored “clearwing” moths (Hemaris spp.) are smaller than the white-lined sphinx moth, and have a wingspan of approximately 2 inches.  Their shaggy appearance and patches of yellow coloration lend a resemblance to large bumble bees.  Characteristic transparent “windows” in the wings help identify these moths.  Several Hemaris species can be encountered in the Great Lakes region with subtle differences in appearance and biology.  Both the “hummingbird clearwing” (Hemaris thysbe) and the “snowberry clearwing” (Hemaris diffinis) can be common, while the “slender clearwing” (Hemaris gracilis) is associated with pine barrens and is rarely encountered.

The hummingbird clearwing moth (Hemaris thysbe) showing the transparent “windows” in the wings. Photo Credit: Andy Reago & Chrissy McClarren; Wikipedia

The “Nessus Sphinx” (Amphion floridensis) is another hummingbird mimic that was commonly reported earlier in the summer.  Although somewhat similar in size and coloration to the Hemaris clearwing species, the Nessus sphinx moth has opaque wings and two distinct yellow bands across the abdomen.

The Nessus sphinx moth (Amphion floridensis) in action. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

In addition to being a joy to observe, sphinx moths are a great example of “non-bee” pollinators.  Their unique behavior and anatomy allows them to form interesting relationships with some of the plants they pollinate.  In an extreme example, the Christmas Star Orchid (Angraecum sesquipedale) from Madagascar possess extremely long tube-like floral structures which contain the nectar.  Upon learning of the unique anatomy of this orchid, the famed naturalist Charles Darwin speculated that a moth with equally long mouthparts must exist to pollinate them.  It took over a century to document, but a sphinx moth wielding foot-long mouthparts was finally observed pollinating the Christmas Star Orchid.

Invasive Species, Moths, Odd Insects, Ornamental Pest, Outdoor Worms, Pollinators, Shrubs, Tree Insects, Uncategorized

Wisconsin’s Top Insect Trends of 2015 (#5 – #1)

In this post, we’re continuing to count-down 2015’s top insect trends in the state.  This is the final post in a three part series.  Part I (2015’s diagnostic lab statistics) can be found here and Part II (Top Insect Trends Numbers 10-6) can be found here.

5) Pollinators
With all the headlines about bees, it’s not surprising to see pollinators in the top insect stories again in 2015.  Similar to other years in the recent past, honeybees and other pollinators have been facing declines.  Unfortunately, Wisconsin saw some of the highest honeybee losses in the country, with over 60% colony loss during the 2014-2015 period.  Some good news over the past year has been the development and release of pollinator protection plans.  A federal pollinator protection plan was released in May with the goals of reducing honeybee losses, increasing the population of Monarch butterflies, and increasing pollinator habitat.  In addition, a Wisconsin pollinator protection plan was announced in 2015, and was just released in January of 2016.   Due to the recent declines and their importance to agriculture in the state and nation, pollinators will continue to be in the spotlight in the future.

A ground nesting bee (Colletes sp.) near the stump of the former President's Oak on the UW-Madison campus. Photo Credit: PJ Liesch
A ground nesting bee near the stump of the former President’s Oak on the UW-Madison campus. Photo Credit: PJ Liesch

4) Spring caterpillars
An unexpected insect trend in the spring of 2015 was the surprising abundance of a number of caterpillar species feeding on plants in the landscape.  Caterpillar species, such as the humped green fruitworm, speckled green fruitworm, eastern tent caterpillar, forest tent caterpillar, gypsy moth caterpillar, and the euonymous caterpillar are typically present to some extent, although their numbers have been low the past few years.  For a number of potential reasons, these species had a great spring and during a period in May and June, caterpillars made up roughly 30% of the cases coming in to the diagnostic lab.  Weather patterns (i.e., rainy weather) and natural predators/parasites/diseases can have significant impacts on caterpillar populations each year, so it’ll be interesting to see if we’re faced with a plethora of caterpillars again in 2016.  Additional details of this story were featured in a blog post last June.

3) Viburnum Leaf Beetle
In terms of a new emerging pest with the potential to impact a commonly planted landscape shrub, Viburnum Leaf Beetle is near the top of the list.  As of late 2014, we only knew of a single infested viburnum bush in northern Milwaukee County, which raised the question: is the infestation small enough to contain and/or eradicate?  Some ground truthing this past spring identified many new infestations in SE Wisconsin, in many cases miles from the original site.  At the moment, the viburnum leaf beetle seems to be centered around the four county area where Milwaukee, Waukesha, Washington, and Ozaukee counties meet.  While this insect only feeds on viburnums (and related plants like Arrowwood), the damage can be significant.  It may be some time before this pest spreads elsewhere in the state, but if you have viburnum plants in your yard in SE Wisconsin, be weary!  Additional details of this case were featured in a post last June.

VLB Damage
“Skeletonizing” feeding damage from adult viburnum leaf beetles. Photo courtesy of Paul Weston, Cornell University, Bugwood.org

2) Brown Marmorated Stink Bug
Populations of the invasive Brown Marmorated Stink Bug increased dramatically in 2015 and this insect takes the overall #2 spot in this list (up from #8 last year).  This invasive species was first spotted in the state in 2010, and each year a handful of lone adults have been found in Wisconsin.  In the fall of 2015, we had more sightings of BMSB (30+), than in the past 5 years combined! (Spoiler: this trend has continued into early 2016)  At this point, the “hot spots” in the state are: Dane County, the greater Milwaukee area, and the Fox River Valley.  In addition to being an indoor nuisance pest, BMSB can also feed on and damage a wide variety of plants in home gardens, agricultural fields and orchards.  In other places in the country, the first reports of plant damage have typically been noted ~3-5 years after the initial detection of this species.  With that said, 2016 could be the year that BMSB really takes off and starts wreaking havoc for gardeners and agricultural growers alike.  Additional details of this case can be found in this post from last October.

1) Magnolia Scale
While scale insects have already been mentioned in the “sucking insects” section (#9 on the list), one species in particular, the Magnolia scale (Neolecanium cornuparvum), seemed to stand out amongst all other insects in 2015.  This species is often present in low numbers in the state, but the conditions must have been perfect for their populations to explode last year.  During the months of June and July, reports of Magnolia scale were coming in on almost a daily basis.  Being one of the unusual scale insects, Magnolia scale adults look more like a fungus than an insect (note the whitish blobs in the image below).  Not only did this bizarre looking species pummel Magnolia shrubs and trees in many parts of the state, but the honeydew produced by these insects rained down below, attracting ants and yellowjackets and leading to the growth of unsightly black sooty mold.  A number of predators, parasites, and diseases typically keep Magnolia scale in check, but with the extremely high infestations noted last year, it’s likely that we’ll continue to see some Magnolia scale activity into 2016.  If you experienced magnolia scales first hand, there’s a helpful factsheet available here.

Magnolia twig coated with whitish, fuzzy magnolia scale adults.
Pollinators

Be Thankful for Insects

As we’re sitting down for the Thanksgiving feast, there’s one thing we should all be thankful for, whether we realize it or not: insects.  It turns out that insects are involved one way or another with many of the foods we’ll be stuffing ourselves with.  Without those very insects, the dinner table would have a drastically different appearance.

Squash Bees (Peponapis pruinosa) inside of a cucurbit flower. These bees are partially responsible for your pumpkin pie. Photo Credit: USDA ARS
Squash Bees (Peponapis pruinosa) inside of a cucurbit flower. These bees are partially responsible for your pumpkin pie and squash dishes. Photo Credit: USDA ARS

Think about the ubiquitous pre-dinner veggie platter at the family get-together.  If you already have seeds of carrots, celery, broccoli, and cauliflower, you can technically grow a batch of these crops just fine.  But with many vegetables, insect pollinators help produce that next batch of seeds.  Then there’s the cheese and cracker appetizer plate.  Being made from wheat (a wind pollinated plant), crackers technically don’t require insects to be produced.  You might also think that cheese (being a dairy product) is also unaffected by insects.  However, insects play a role in the production of alfalfa, which is a common food source for cows.  Without alfalfa, cheese, butter, and other dairy products would be harder to produce, and could be tough to find at the grocery store.  Oh, and without insects as pollinators, we wouldn’t have the almonds on the outside that smoked cheese log anymore.

Some of the items from the main course don’t rely on insects to make it to the table: turkey and potatoes.  Technically, wild turkeys can feed on insects as part of their diet, although they can feed on many other things as well.  If you’ve recently seen The Martian, you’ll remember astronaut Mark Whatney growing potatoes sans insects to survive, so those mashed potatoes would still make it to the table.  Bread and dinner rolls (from wind-pollinated wheat) would still be around.  We could also have certain vegetables that can self-pollinate without insects, such as lima beans (who doesn’t love a great big helping of lima beans…).  However, some big players on the dinner table rely on insects for pollination, including the many types of squash.  One of the most crucial Thanksgiving dishes, the cranberry sauce, wouldn’t be around as cranberries rely on bees for pollination.  It’d be a sad Thanksgiving if there were no cranberry sauce.

As we finish dinner and get ready to watch football, it’ll be about time for dessert and coffee to perk up. Unfortunately, that’s where some bad news comes in.  Without insect pollinators, we wouldn’t have pumpkins to make the traditional pumpkin pie, or some of the spices, like nutmeg, to flavor it.  The whipped cream to go on top?  Well that’s one of those dairy products that could be hard to come by in a world without alfalfa.  Maybe you don’t care for pumpkin pie and prefer apple, cherry or blueberry pie instead?  Those fruits all rely on insect pollinators as well.  Maybe we’ll forget about dessert and go right for that coffee so we don’t fall asleep on the couch.  Just keep in mind that insects are also responsible for the pollination of coffee plants.

When it comes to Thanksgiving tomorrow, be thankful for family, friends, good health, and also the insects that helped put a lot of that great food on the table.

Butterflies, Pollinators

The Plight of the Monarchs

Just like the bees, the beloved Monarch (Danaus plexippus), is facing declines in North America.  Unlike the bee declines, which seem to be the result of a complex amalgam of factors, a major factor jumps out when it comes to monarch declines: habitat loss.  Simply put, we’ve gotten rid of much of the formerly ubiquitous milkweed in the Midwest.  There’s a number of reasons for this, ranging from continued land development, farm subsidies that have resulted in the cultivation of non-crop land, and heavy use of herbicide resistant crop varieties.  One scientific report suggests that the Midwest has lost nearly 60% of its milkweed over the past fifteen years.

Reared adult monarch prior to release, August 2008; Photo credit: PJ Liesch

We all probably learned the general story of the monarch in elementary school: a spring northward migration, milkweed, eggs, more milkweed, striped caterpillars, even more milkweed, orange and black butterflies, and finally migration down to Mexico after a few generations (there’s a great migration video here).  It’s bad enough that the sole summer food source of the monarchs (milkweed) has been disappearing, but monarchs are actually fighting a multi-front battle, as their overwintering habitat is disappearing as well.  Over the past few decades, much of the overwintering territory in Mexico has been lost, degraded, and fragmented by logging (both large and small scale).  What’s really concerning is that the overwintering territory isn’t all that big to begin with, making the insects vulnerable to extreme weather events.  A brutal winter storm in January of 2002 killed roughly 75% of the monarchs at some overwintering sites.  If monarchs keep getting squished into smaller and smaller areas, all it could take is a few bad winter storms to crash their numbers. Talk about putting all your eggs into one basket. . .

So why the fuss about monarchs now?
Over the past two years, the number of monarchs overwintering in Mexico has been the lowest in the history of the annual surveys.

Monarch Population Chart

With enough support, could we also pull the iconic monarch out of harms way?  Having the assistance of the President of the United States certainly helps.  Just yesterday, the white house announced that the Pollinator Task Force (created in 2014) has released its plan to help pollinators.  The three main goals of the plan are: 1) reduce honey bee losses to sustainable levels, 2) preserve the monarch population in the US, and 3) increase and improve pollinator habitat (full details here).

This isn’t the first time we’ve recognized a species at risk and created a recovery plan.  A classic success story: the iconic bald eagle.  It’s estimated that in the mid 1900’s there were just over 400 pairs of bald eagles left in the contiguous US.  These days, anyone passing through Sauk City, can tell you bald eagles have certainly rebounded.

While the Pollinator Task Force’s plan will take some time, there are things we can all do to immediately provide assistance for monarchs:
1) Plant milkweed to create a habitat for monarchs
2) Get involved with citizen science projects to educate ourselves and others
3) Use caution when using pesticides in the landscape to minimize impacts to monarchs, bees, and other beneficial species

 

Flowers, Pollinators

Busy as a (Native) Bee

I think it’s safe to say that just about everyone knows and appreciates honey bees (who doesn’t love honey after all). Humans have a long history with honey bees and European settlers purposefully brought them over to the Americas. However, there’s another piece of the pollinator picture which is often overlooked and under appreciated: our many native bees.

Native Bee_opt
A native bee visiting flowers in the Allen Centennial Gardens on the UW-Madison campus, July, 2014. Photo Credit: PJ Liesch

How could they go unnoticed? A bee’s a bee, right?
Not quite—If you take the time to learn about Wisconsin’s bees, you might be surprised to discover that we have approximately 500 species of bees in Wisconsin alone. (Then there are the many flies and wasps that are often mistaken for bees, but I’ll save mimicry for another day.)  A common example of a native bee would be the metallic green “sweat bees” (Family Halictidae), although many different species exist within that family alone.

Most of our bee species are native, solitary creatures with their own unique habits.  With their solitary nature, each female makes her own nest and there’s no colony of relatives to defend (unlike honeybees).  With that said, our native bees tend to be rather docile, allowing for plenty of opportunities to observe them foraging at flowers or constructing their nests. Depending on the species, our native bees tend to nest in the ground (the females dig tunnels) or inside of hollow chambers.  These hollow chambers could be a tunnel made in wood or a hollow plant stem. Regardless of the nesting site, the story is similar: the female bees gather food (pollen and nectar) to stash away in the nests for their young. Depending on the species of native bee and the type of plants in the area, native bees can actually be more effective at pollinating than honey bees. Thus, the importance of these native bees is often overlooked and under appreciated.

A ground nesting bee (Colletes sp.) near the stump of the former President's Oak on the UW-Madison campus. Photo Credit: PJ Liesch
A ground nesting bee near the stump of the former President’s Oak on the UW-Madison campus. Photo Credit: PJ Liesch

Like honey bees, many native bees are facing declines for a number of reasons. One of the best things to do is to learn about native bees and other pollinators and to make your yard pollinator friendly by providing floral resources and nesting habitat.