“No one and I mean no one knows what they are”, states this reader about the ‘little flat thingie[s]’ he discovered hanging from his cottonwood trees. The picture below shows the organism on the flat of our reader’s finger, showing us how minuscule this creature is.
“I have three cottonwood trees,” he continues. “In the spring and fall they get this thin strain of silk hanging down with a little flat thingie at the end. No webs in the trees. The leaves have holes in them but no worms or bugs can be found. Just this thin silk strain hanging down.”
Now, given how little the bug is, as well as the lack of focus on its body in the photo (making it impossible to see its finer details), we will not be able to provide a confident identification of it. Generally speaking, there are many species of caterpillars that can produce silken threads from which they dangle, such as inchworms. In fact, we recently published an “article on oak leafrollers” (a type of inchworm), in which we discuss these curious little critters. That might indeed be what our reader found, as their descriptions do match up nicely.
Oak leaf rollers are moths, and they get their name from the caterpillars’ tendency to roll together leaves that they can take shelter in and feed in peace. Some leafroller caterpillars have even been known to use their silk to tie multiple leaves together to make bigger shelters, showing some rather impressive ingenuity, if we may say so ourselves.
The caterpillars tend to be green in color, but can often appear yellow or white in certain lighting. That said, they do not look ‘flat’ like the creatures our reader mentions, so we do not know if these really could be leafroller caterpillars, or if they just appear flat to our reader because they are so small. Either way, the organism in our reader’s photo appears to be black. So, while we doubt that the bugs he found are specifically oak leafroller caterpillars, they could be some other species of inchworm.
Now, while leafroller caterpillars (and many other species of caterpillars that live in trees) are defoliators and can cause harm to trees (though only short-term), they are completely harmless to humans and pets, so our reader needs not worry in that vein.
In conclusion, we do not know what the small, ‘flat’, black creatures that our reader found are. Based on the fact that they are hanging from the trees by silken threads, we would guess that they are leafroller caterpillars, or some other type of inchworm. Although we were not able to provide a concrete identification, we hope that this article helps nonetheless. We wish our reader the best.
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