“What are these little worm-like bugs?” asks this reader in her submission regarding the horde of tiny, black creatures pictured below. “They literally appeared overnight, and were attached to the cord on my blinds. They stick off horizontally and kinda wiggle.” Based on the number of these found, as well as their appearance, we would say that these are newly-hatched moth caterpillars, specifically American ermine moth caterpillars, though they could also be fall armyworms. At this early on in their life cycle, it is difficult to tell the difference between the two species.
In any case, both moth species behave similarly at this stage: the larvae all hatch together in one spot and will move as one large group in search of food. Luckily for our reader, neither species of caterpillar likes food that would grow inside a home, so the infestation should not spread if she simply moves all the caterpillars outside. American ermine moth caterpillars feed on shrubs, weeds and fruit trees, while fall armyworms are far less picky eaters. In fact, fall armyworms are known to munch on over 300 different plant species, which includes a lot of crops, making them a notorious pest among farmers, especially since they travel in such large groups.
So, our reader must be wondering, if the caterpillars don’t want to eat anything in her home, why are they there? Well, it is not entirely uncommon for people to find newly-hatched ermine moth caterpillars or armyworms in their home: we have received a handful of submissions from other readers finding the same thing. The reason this happens is likely because the mother moth chooses to lay her eggs in a house as it provides a safe environment to do so, sheltered from the wind and from predators. Alternatively, a mother moth may simply accidentally find its way into someone’s house, as moths do, and lay her eggs there. In any case, they are not looking to infest the home. The caterpillars want out, so that is the best thing our reader can do for them.
To conclude, the horde of tiny black worm-like creatures our reader found on the cord of her blinds are moth caterpillars, and we think they are either American ermine moth caterpillars or fall armyworms. Neither species is harmless nor are they household pests, but if our reader has a garden, it is probably best not to release the caterpillars there. We hope this helps and we wish our reader the very best!
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