Monday, September 28, 2009

Indoor Insects of Autumn (part 1 of 4)


This is the first in a four-part series of entries addressing insects frequently seen indoors at this time of year when they seek shelter for hibernation during the colder months. This entry will introduce the “western conifer seed bug,” Leptoglossus occidentalis.

Western conifer seed bugs, despite their common name, now occur over the entire northern half of the United States and adjacent southern Canada. They were initially a truly western species, but have since spread eastward. They were first recorded in Connecticut in 1985, for example.

These insects, members of the “leaf-footed bug” family Coreidae, are frequently mistaken for “kissing bugs,” blood-feeding assassin bugs in the genus Triatoma in the family Reduviidae. Conifer seed bugs are not the least bit dangerous, however, feeding on the seeds and developing cones of pines and other conifers. The long hind legs of these insects, with the slightly flared “bell-bottoms” appearance of their “ankles,” are a good field mark to look for in trying to identify these true bugs.

The western conifer seed bug is a fairly large, conspicuous insect roughly twenty millimeters long, and it flies with a loud, droning sound that makes it intimidating and unwelcome as an indoor guest. Furthermore, they are equipped with a pair of scent glands on the underside of the thorax. The bugs don’t hesitate to deploy their defense when molested, emitting a permeating pungent odor that deters all but the most determined predators.

Leaf-footed bugs are not without their enemies, though, chief among them being tachinid flies in the genus Trichopoda. The female fly lays at least one white, dome-shaped egg atop its host where it cannot be easily wiped off. The egg is in fact firmly adhered to the bug’s exoskeleton. Adult insects are doomed when the fly larva hatches and bores into its host’s body where it lives as an internal parasite. Immature bugs (nymphs) may occasionally escape the fly’s assault if they molt the exoskeleton before the egg hatches, though the bugs cannot molt at will, only when growth demands it.

Human beings can best deal with the western conifer seed bug by excluding them from their homes. This means repairing worn weatherstripping on doors, fixing holes in window screens, and blocking off other openings where the insects might enter, such as where plumbing and electrical conduits enter or exit the residence. Should one of the bugs still make an appearance, simply usher it gently into a container and take it outdoors. Normally, these bugs hibernate in snug, natural places such as under bark on logs, in woodpiles, rodent nests, and similar niches.

25 comments:

  1. Thanks for this post. I was curious as to what this insect was that I frequently see on my nature hikes. I love your idea for the "indoor insect" series as well! I'm looking foward to future posts.

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  2. Thank you, Shanda, I appreciate the compliments:-) Glad you found this post helpful.

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  3. Great post Eric. Fascinating little bug. You mentioned they are spreading their range to include the East. Does this include Missouri? If not yet seen this particular species, so I was wondering.

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  4. Hi, MoBugs. This particular species seems confined to the northern tier of states. You have at least two other species of Leptoglossus down there, though.

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  5. Thanks for the info. I didn't think we had them, I am outside so much I would have thought I would have spotted one if we did. I have seen some similar, so perhaps those are the two species you are referring to.

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  6. I'm happy/disgusted to report that these little guys have taken over my 2nd floor bedroom and bathroom! I'm on the North Shore of MA and have been gently ushering any stragglers I can find with all my might, but still have daily tour groups headed veeerrrry sllooooowwwwlllly from one side of the room to the other. I don't want to whip out any bug spray, but starting to lose patience with their daily parades across my bed and clean laundry.

    Finally having a professional come on Wednesday to find out where they are getting in (no obvious screens or holes that I can find). Between that and persistent removal I'm hopeful the siege will end shortly without too many fatalities. I'm not a murderess you know. I am, however, a complete insectophobe, but having a little info about my unwelcome houseguests comforts me. Great site!

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  7. Thank you for enlightening me about my fall guests. I admire these harmlesss slow moving creatures. Theyve become a welcome sign of the change of seasons and cold weather coming.I've never seen one anywhere but at my home in NY untill last week in Amherst, MA. My husband thinks they are ancient/prehistoric looking. We never kill them but sometimes find them crushed in the doorways. I make about ten trips a day escorting one out of my home. Even the cats aren't interested in them! My daughter wants to bring one to show and tell and I now have some info for her. Interesting.

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  8. Thank you for this. We have distrusted these bugs because of their similarity to assassin bugs. Glad to know we can co habitate with them without fear.

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  9. Also North Shore of MA ...... also seeing them fairly commonly of late. A few inside. NOT Asian long-horned beetles. Happy.
    Thanks for a good ID picture!

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  10. Yikes! These bugs are invading my home in Southern NH! They may not be harmful, but their size is very intimidating!

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    1. I can appreciate that! They are pretty noisy when they fly, too.

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  11. glad this info is still available. I found one in my home (in Ohio) and was mortified, thinking it was a 'Kissing Bug'. The long proboscis conjured up scary thoughts. Image searches showed the kissing bug to not have the 'leafy ankles' or such squared shoulders however. Your image was a dead ringer and the info was very helpful and put my mind at ease. Thanks for your post.

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    1. You are most welcome! Yes, these are often confused with assassin bugs.

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    2. So do the assassin bug(kissing bug) even live in Connecticut or are they just isolated to the southern states?

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    3. Here's my blog on the Masked Hunter, Reduvius personatus, that is indeed found in Connecticut: http://bugeric.blogspot.com/2013/01/true-bug-tuesday-masked-hunter.html. Meanwhile, the Black Corsair, Melanolestes picipes, also occurs in New England. The Eastern Blood-sucking Conenose, Triatoma sanguisuga, is also recorded from your area, but it is uncommon.

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  12. Do they secrete a blue fluid when squished? I am terrified I had a kissing bug in my room but hoping it's just one of these!

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    1. Danielle: Obviously, I don't advocate squashing insects, so I can't answer your question....but kissing bugs are found only in the southwest U.S. and east of the Mississippi River, north to about Ohio. Kissing bugs are seen mostly in the spring and summer, whereas Western Conifer Seed Bug is most obvious in fall (I have seen several in the past week here in Colorado).

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  13. We recently moved into a farmhouse that was built in 1900. Our two year old had some weird bites on her neck and a few days later I saw what I now think is a Western Conifer Seed Bug stalking across her bedroom carpet. I'm a biologist so I've taken entomology (cue kissing bug panic). They were congregating on our bedroom window last week and I caught one in the kitchen today. Taking it to our local university entomology lab to be sure, but will definitely sleep better tonight knowing that the mosquitos are probably the only blood suckers we need to worry about!

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  14. Omg I'm so glad I found this site:) our home & all the screens are covered with this good size creature. I am not a bug killer AT ALL, so I have been kicking them back outside where I can handle seeing them. We are also in Massachusetts & very happy we are not alone.

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  15. Panic had subsided. Found two in the last week and was convinced I had kissing bugs until I found this article. I'm located in a woodsy part of Boston chock full of conifer trees. This explanation makes much more sense than my previous fears

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  16. So incredibly glad to have found this site. I had captured one of these bugs and had remembered various articles about kissing bugs that generally matched the same description I the bug I'd caught. I can sleep far easier knowing the bug was actually harmless. Thanks again!

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    1. Thank you for the positive and appreciative feedback!

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  17. Thank you so much for this post. A friend of mine found one in her house and asked me if it was a kissing bug, but it didn't quite match the look of one, almost but not quite. You helped me to put her mind at ease(she has 5 children and was concerned)

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    1. Happy I could help! Thank you for the compliments and sharing your friend's story.

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