A gray caterpillar-like creature with a glossy black head was found by this reader, who asks what kind of “worm” it is and where it is coming from. This article will do its best to answer these questions and provide some insightful information on this specific organism.
The short answer to our reader’s first question is that this is an armyworm, or at least, that is what we suspect it is. To be more specific, we think this is a young fall armyworm. Armyworms are caterpillars of the armyworm moth. Their eggs are laid in clusters, and likewise they live in clusters too. Upon hatching, the larvae will travel in groups, or ‘armies’ (hence the name), throughout maturation. When eggs or larvae are found inside the home, it is usually because the mother moth laid her eggs there because it provided shelter, or because it accidentally wound up inside when it was time to lay her eggs. Otherwise armyworms will really have no interest in anything in the home. Of course, our reader only reported finding one caterpillar, so it could be that this larva just wandered into her home. Fall armyworms are not parasites, are not poisonous, and pose virtually no threat to human health. It should be noted that since armyworm eggs are laid in clusters, once hatched, it can seem like one’s home is infested with them, but one will find that once the larvae are moved outside, they will not return. For that reason, we recommend that our reader simply takes the larva she found outside where there is some plant it can chew on.
That being said, our reader should probably not leave the larva in her neighbor’s garden, or her own garden for that matter, unless she has a vendetta against them. Whilst being utterly harmless to humans and pets, fall armyworms are among the most notorious agricultural pests you can come across. There have been countless studies, scholarly papers and news articles written about the control of fall armyworms on farms. In fact, the FAO (Food and Agriculture Organization of the United Nations) deemed fall armyworms an “international threat” and developed a ‘Global Action for FAW Control’ (FAW being an acronym of ‘fall armyworm’) plan that aims to “establish global coordination” in the fight against fall armyworms. All of this is because fall armyworms, especially because they travel in groups, are some of the most dangerously efficient eaters of any caterpillar species. And since the egg clusters are so large, their numbers spread so quickly as well. In fact, the mother moth can lay up to 200 eggs at a time, and up to 1000 eggs in her lifetime!
To conclude, the “worm” our reader found is a young fall armyworm. This little critter likely just wandered in through an open door or through a crack in a window screen. Of course, if our reader finds loads more larvae, than it is safe to say that they probably hatched inside the home. Either way, there is no need to fret, as armyworms will not eat houseplants and have little to no interest in staying inside the home. They want to get out and feed on the natural world! We hope that this article sufficiently answered our reader’s question and that she knows she can reach out to us with any further questions about anything worm-related.