Conifer seed bugs

conifer-seed-bug-photo-by-whitney-cranshawIrene Shonle, Director CSU Extension
Gilpin County

As the days cool and we head into fall, many creatures seek to take refuge in our warm homes including mice, cluster flies, and other insects.  One bug that has been drawing a lot of attention recently is the conifer seed bug.  It is a fairly large (5/8th– 3/4 th inch), somewhat awkward-looking insect with long antennae in the leaf footed bug family.  While they are harmless and never bite people, they do fly around and can spray a smelly piney odor when provoked.  I have had several people call me about them, and I was even awakened last night by one buzzing loudly in my ear, tangling in my hair, and finally spraying on my pillow.  I knew before I even got the lights on who the culprit was, just by the smell—which was reassuring, but still not very pleasant.

These insects usually overwinter outdoors under debris, but will readily enter houses in search of shelter.  In either case, they are semidormant. They neither reproduce nor feed, but rather live off fat reserves. It can be difficult to fully exclude them –  it is the usual story of trying to seal off all cracks and crannies and other entry routes and keeping screens on windows, particularly in September and early October. I realize that can be nearly impossible with some of our old cabins.  The good news is that they don’t breed inside houses, and will often die within a couple of weeks if they can’t find access to water.  Vacuuming, swatting them or letting them out a window are the best control measures once they are already in the house.

Here’s a little about their life history from the CSU Extension fact sheet by Whitney Cranshaw. Conifer seed bugs primarily feed and develop on seeds of various trees and shrubs. They prefer pines, Douglas-fir and other conifers but feed on the developing seeds and fruits of a wide variety of plants, including dogwood and sumac. In spring, the insects move to trees and feed on male flowers and year-old cones. Beginning in late May, females lay eggs glued in small groups to needles and leaves. The immature or nymph stages somewhat resemble wingless adults. Nymphs feed on the seeds through the summer. They become mature in August and September. Adults continue to feed on cones until they move to winter shelter. There is only one generation per year.

So, if one of these bugs comes to a windowsill in your house, there’s no need to worry.  Just get out your vacuum or open a window, and know you’ve seen a little more of our local fauna.

The CSU Gilpin County Extension Office is located at the Exhibit Barn, 230 Norton Drive, Black Hawk, CO 80422, 303-582-9106, Colorado State University Extension provides unbiased, research-based information about, horticulture, natural resources, and 4-H youth development. Colorado State University Extension is dedicated to serving all people on an equal and nondiscriminatory basis.