What were Wisconsin’s top insect trends of 2015? In this post, we’ll look at the first half of our count-down.
This is the second post in a three part series. The first post of the series (2015’s diagnostic lab statistics) can be found here.
10) Mosquitoes and ticks:
Like most years, Wisconsin had a pretty good mosquito season. Overall, we were close to the average rainfall mark during much of the year, which meant the typical batch of mosquitoes starting after Memorial Day. In many parts of the state, mosquitoes were prevalent throughout June, July, and August. However, this is Wisconsin after all, and mosquitoes seem to be one pillar of summer culture along with beer, cookouts, and fishing. The silver lining of the mosquito story is the fact that West Nile Cases were low for the year, with only four confirmed human cases reported in the state in 2015.
While there wasn’t anything out of the ordinary with the mosquitoes last year, ticks seemed to have a particularly good year in the state. Deer ticks, which can vector Lyme disease can be found essentially statewide. From the standpoint of an emerging health threat, deer tick populations have exploded in the past few decades (our first deer tick wasn’t found in the state until the 1960’s). A recent nation-wide study found that deer ticks were found in nearly half of the counties in the U.S. One of the more alarming trends is urban encroachment. Historically, ticks seemed to be the type of creature you’d pick up if you were out hunting or hiking through the woods. In the recent past, we’ve noticed an increase of ticks found in more urban environments, such as parks and backyards. With roughly 40% of the adult ticks in Wisconsin carrying the microorganism responsible for Lyme Disease, this is an issue that will continue to exist in the state for years to come.
9) “Sucking Insects”
A certain group of insects (the Order Hemiptera) are sometimes known as the “sucking insects” because they possess tube-like mouthparts which are used by many species use to drink fluids from plants. Two of the members of this group, the aphids and the scale insects had a great year in 2015. When these insects feed on plants, a common sign is the presence of sticky, sugary honeydew, which attracts ants and yellowjackets, and can result in the growth of black sooty mold. Aphids and scale insects are common and typically present in low numbers, but the conditions must have been just right for their populations to thrive in 2015. As a result, there were many reports throughout the state of honeydew “raining” down from trees and shrubs onto vehicles, decks, outdoor furniture, and people below. If you felt “rain” on a sunny day last summer, the actual cause may have been honeydew dripping down from aphids or scales in the trees above!
8) Long Lost Pests: Japanese Beetle and Gypsy Moth
Two of our best-known landscape pests, the Japanese Beetle and the Gypsy Moth had been very quiet in 2014, but resurfaced last year. Japanese beetles had been low across the state in 2014, likely due to the brutal winter of 2013-14 killing many of the soil-dwelling grubs. While we did see an increase in beetle activity in 2015 compared to 2014, their numbers still seemed low compared to the long term average. However, with a milder el Niño winter, it’s possible that we could see increased winter survival and higher Japanese beetle populations in 2016.
Gypsy Moth populations have been low the past few years in Wisconsin. Damp spring conditions can result in a fungal disease killing many of the caterpillars, which likely helped lessen populations in the recent past. It’s also not unusual for some long-term cyclic patterns to be involved with insect populations. For a number of potential reasons, Gypsy Moth populations seemed to rebound a bit in 2015, and many reports of sightings and damage came in to the diagnostic lab, particularly from the south central portion of the state (Dane, Rock, Walworth Counties). Because Gypsy Moth can be a destructive defoliator of hardwood trees, it’ll be good to keep an eye out for this one in 2016 to see if the populations continue to climb.
7) Emerald Ash Borer
This is our most destructive forest pest in the state, and unfortunately, there doesn’t seem to be anything capable of completely stopping this pest. While we didn’t see many additional counties added to the quarantine map in 2015, there were many municipalities that detected EAB for the first time. At the moment, 39 of the 72 Wisconsin counties are quarantined for EAB and this number will continue to increase over time. Like Dutch Elm Disease in the past, Emerald Ash Borer is changing and will continue to change the appearance of our urban forests and woodlands for years to come.
6) Spotted Wing Drosophila
This invasive pest first showed up in the state in 2010, and became a significant fruit pest almost immediately. Since its introduction, SWD has spread widely and can be found in most counties in Wisconsin. Very similar to 2014, SWD was detected in dozens of counties across the state. SWD can attack a wide variety of fruit, but due to the fact that this insect doesn’t seem to become active until July, the late-season raspberry and blackberry crops are hit the hardest. Luckily Wisconsin’s famous cranberry crop does not seem to be favored by this invasive pest.
Up Next, Part III: Wisconsin’s Top Insect Trends of 2015 (Numbers 5-1)