Tuesday, March 16, 2010

Bugs in Winter? You Bet!

 Winter Stoneflies

I always dread the end of summer. The bugs slowly start to disappear and by mid-fall, they seem to be all gone. This past autumn was a definite exception, with the ladybugs still being out in force in the middle of November! But, inevitably, winter arrives and my days of bug hunting come to an end for what seems like forever. Lucky for me, I discovered the existence of small winter stoneflies. I didn't actually "discover" them... but I did stumble across them in the woods one day. Hundreds upon hundreds of them - all crawling on the snow toward some mysterious destination. Wow! Bugs in winter! I love it.
So after taking a plethora of shots, I get home to research these new little critters I've found. They were quite hard to photograph, as I had little light, they were very speedy, and were only about 1 cm in length. Some seemed to be flying, but they were not very good at it. I watched for a good while to see where they were going. They all seemed to be going in the same general direction, possibly to find mates or food. I noticed many were scurrying up trees and some had even begun mating. I wish my photos were better, but you'll get the idea of what they look like anyway.

From the reading I've done on them, I have discovered some interesting facts, or as I like to call them...

...Juicy Tidbits

  • Stoneflies larvae are aquatic and are commonly called naiads (pronounced NIGH-ads).

  • Stoneflies (form the order Plecoptera) are sensitive to pollution. So are mayflies (Ephemeroptera) and caddisflies (Trichoptera). Combined, these insects are the "EPT" indicator species and are used to determine the health of streams, rivers and other water sources.

  • The stoneflies that I found are believed to be of the genus Allocapnia, according to the experts at http://www.bugguide.net/

  • Adults emerge from rivers and streams during the month of February, and live from a few days to a few weeks. Enough time to find a mate and lay eggs.

  • They feed on algae found on tree bark. In the females case, this algae is needed for egg development.

  • Once eggs are developed, females return to their water source to wash the eggs from their body by flying along the surface of the water and dipping their abdomen into the water.

  • Their eggs hatch about three weeks later. The resulting larvae feed on algae and fungi in the water for a few weeks. After this time, they bury themselves at the bottom for a brief period of inactivity that lasts the summer. This is called a period of diapause - and is a suspension of development. Feeding resumes in the fall and the adults emerge in February. Cycle complete!
So, from what I've read, it makes complete sense that the stoneflies were climbing trees - it's their food source!

I love it when I find an insect that is new to me. The whole process of trying to i.d. it from my many handbooks, to the hours of "googling" that I do to learn all I can about my new little find. And then, finally, the sharing of what I've learned and the photos I took. If you'd like to learn more, visit the websites I've mentioned below, or better yet, get yourself a trusty little insect field guide.

Some stonefly websites that you may enjoy are:
Two books that I used for factual information of the stonefly were:
1) The Discovery Channel's "Insects and Spiders", an Explore Your World Handbook (pg. 138)
2) Kaufman's "Field Guide to Insect of North America" by Eric R. Eaton and Kenn Kaufman (pg. 60)


  1. I may have overlooked it in the post, but did you state what the approximate air temperature was when you snapped these pics? Stone Flies must have a very low chill coma point. However, I know that physics work a bit differently at that scale. Perhaps just a couple molecules of the insects claws are touching the ice. Maybe reducing the level of cold conduction as they scurry about.

  2. Hi Tim,

    It was a rather warm day when the stoneflies where out in abundance -- Probably about 5 degrees celsius (41 F). Kaufman's "Field Guide to Insects of North America" indicates that small winter stoneflies can be active at temperatures as low as -6 degrees celsius (20 F). I am unsure as to how much contact there is between the stonefly and the snow, but they did not seem hampered by the snow by any means.

    Thanks for the comment!

  3. We get these bugs every March We live right beside the river. We call them snow bugs because we see them on the snow, the buggers also come into the house, walking on the ceiling and walls. They are also all over the outside of the house eves. walls and the garage. blahhhhh, They do flyto the ground but usually when they are blown off the wall or the doorway.