P&PDL Picture of the Week for
December 27, 2004

Most insects are smart enough to get out of the cold

Tim Gibb, Insect Diagnostician, Department of Entomology , Purdue University

A rule of thumb is that insects are active in the spring, summer, and fall, but by the time winter hits, they are either smart enough to come in out of the cold or they have figured out a way to ‘sleep’ through it.   This rule is followed by 99% of all insects, however, there is one exception that is sometimes seen on sunny days in late winter. People may notice thousands of tiny black specks jumping around on the snow.  Because of the unusual timing and location of these insects, they are often sent into our laboratory for identification and psychological evaluation.

These insects are usually found to be Snow fleas (although we cannot vouch for their sanity).  Snow fleas (Poduridae, Achorutes nivicolus), derive their common name because they actually live in and jump around in the snow.  This jumping insect bears no other similarity with the common cat or dog flea, does not harm people or pets and seldom even get into homes.  Rather, Snow fleas belong to a primitive group of insects called springtails (Collembola) that do not even possess wings, but feed on microscopic decaying bits of algae, fungi and bacteria that they find on the surface of the snow.  They move about by using a spring-like mechanism or tail at the back of the body (Figure 3). 

This appendage is bent forward, underneath the insect and when released all at once, propels the insect into the air and gives the appearance of a flea-like jump.

What makes these insects so unique is that Snow fleas are most active from November through March, precisely the time that most other insects are not. They may not be real smart, but they are certainly adaptable.

Snow fleas are simply one more fascinating example of nature’s exceptions to the rule.

Click image to enlarge

Figure 1

Figure 2

Figure 3

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service