Identifying Insects by Smell

The title might sound a bit far fetched at first, but it turns out that many insects produce odoriferous chemicals for a variety of reasons.  Stink bugs are a classic example of insects that can produce pungent chemicals, although many related insects in the order Hemiptera also have scent glands.  Many beetles can also produce strong odors when disturbed, and I recently experienced this firsthand after picking up a brilliantly colored Chlaenius ground beetle in my yard.

From my experience, the scents associated with insects aren’t particularly pleasant.  However, exceptions to this observation do exist.  Take the larger yellow ant (Lasius interjectus) for example.  These ants produce a pleasant lemony scent resembling the aroma of citronella candles, hence their other nickname of “citronella ants”.  While there aren’t many cases where an insect can readily be identified by its smell, the citronella ant is probably at the top of the list.

Citronella Ant
Citronella Ant (Lasius interjectus); Photo credit PJ Liesch

Unless you’re flipping over rocks looking for them, you probably won’t bump into citronella ants.  However, they will occasionally nest beneath a concrete slab in a home and end futilely swarming in someone’s basement.  This situation recently presented itself in the lab, and the scent emanating from the ziploc bag gave away the ants’ identity even before I had the specimens under the microscope.