Thousands of tiny moths dead in Park County cabin this spring

Asked June 27, 2018, 5:49 AM EDT

We have a seasonal cabin near Tarryall in Park County. When we opened it up in June there were thousands of tiny dead moths all over the cabin...mostly near windows and glass doors. They are light colored tan/whitish/silver with wings closed, tiny, slender. We had them in 2017 as well but no where near as many. From articles I have found they may look like “vagabond moths” in articles about an invasion in Greeley a few years ago. (W. Cranshaw quoted in Greeley news article.) .
I have a lot of questions about them...we were really freaked out by the masses of them...took hours to vacuum and sweep up. Would we have those moths there at our altitude? If not what are they? I assume they are coming from outside. We do leave one window very slightly cracked all year. Can we prevent them by treating inside or outside? When are they coming in? Are they a threat to our food, pets, fabrics or animal fur...like bear skin rug or deer taxidermy? They are NOT in our pantry/cabinets and we keep virtually no food there in winter and we don’t see any alive. They aren’t termites. I feel like I may have seen some in our firewood stack last fall...not sure...all local aspen and pine from our land. Some is kept on deck near windows and doors. Any help you can give would be appreciated. I may be able to find some remaining and take a picture to send.Thanks for you’re time. Amy S

Park County Colorado

2 Responses

I can not be very sure on this since no photos were submitted with this.

However, at high elevation sites such as this I have sometimes seen samples in homes of small moths that develop as leafminers on leaves of aspens, cottonwoods and willows. The caterpillars develop within the leaves, producing little tunnels but causing no significant harm to the plants. The adults then sheletred places to survive winter, which can include buildings.

If that is the case, and I can not think of anything else that would produce such large numbers of moths in this situation, then this is just a situation where you have an insect that is a nuisance invader that temporarily uses homes for shelter, but does not reproduce within homes nor feed on anything wihtin the building, and is harmless.

These moths are usually in the family Gracillaridae, which contains a great many species. For images of what members of this family may look like see: https://bugguide.net/node/view/7246/bgimage