Thermodynamic Mysteries: Invasion of the Seed Bugs: Western Conifer Seed Bugs and Thermal Radiation Part One

Thermodynamic Mysteries: Invasion of the Seed Bugs: Western Conifer Seed Bugs and Thermal Radiation Part One
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Fall approaches in the Northern part of the United States, and in Canada. Many view it with pleasure - the changing leaves, the crispness of the air, the start of a new TV season. Christmas will soon be here. Sports fans think of the World Series, football, and the advent of hockey.

There are gloomy aspects to its approach. Children may view the resumption of school with glumness. Flu season is nigh. And then - there is the invasion of Leptoglossus occidentalis, the western conifer seed bug.

March of the Seed Bugs

The western conifer seed bug is a large insect, about three quarters of an inch at its maximum size, with a disconcerting habit. In late summer and the beginning of fall, when it starts to turn cold, it begins showing up in homes, laboratories, government buildings, and schools. In any building. It is injudicious and indiscriminate in where it chooses to go.

Seed bugs do not breed indoors, and do not feed. They don’t bite, and they don’t sting. Neither do they damage items. They will cluster outside of buildings, especially around windows and doors. Large numbers may enter your home at the same time,

There are no know insecticides that can control them, and indeed one is advised against using any, since no tests have been devised yet. The recommended response is swatting and vacuuming. Be careful when you disturb them, lest they emit an odor which has earned them the well deserved moniker of “stink bug”. They also buzz noisily when flying, and their flight patterns are reminiscent of a bumblebee. All the while, these reddish-brown insects have an appearance which only a mother or dedicated entomologist could love.

Western conifer seed bugs were first spotted in Pennsylvania in 1992. Since then, they have been marching relentlessly ever eastward, in their own version of Manifest Destiny.

Pest Control?

The only defense against allowing them ingress into your home is to diligently caulk where you find cracks, and to seal around openings such as windows and doors. Other recommendations include replacing screens on windows and fireplaces. Efforts to prevent its invasion however, reminds one of the Borg on Star Trek. They are coming, they are relentless, and they WILL get inside.

A Thermodynamic Mystery?

But what is it that attracts the bugs to buildings once it begins to get cold? Could it be heat? This is a question asked by a team led by behavioral ecologist Dr. Stephen Takacs at Simon Fraser University. To answer it, they began examining the eating habits of the insect. What they found was an answer in the affirmative; the heat transfer mechanism known as thermal radiation is indeed the culprit. What is the relation between the ability of western conifer seed bugs to foray for their favorite food and thermal radiation? We will examine this in part two.


Washington State University Stevens County Extension

Pennsylvania State University Department of Entomology

Image Credits

Western Conifer Seed Bug Stevens County Extension WSU