“Do I need to kill them or let them do their thing?” asks this reader in her submission regarding the colorful and bushy worm-like creatures pictured below. “I am tolerant until it gets to the point where they’re eating plants down to the dirt. If you can identify them and advise me on treatment, I would greatly appreciate it. I live in rural south Texas, Victoria County, zone 9b. The photo on the leaf is about 1”, while the one on the concrete is almost 3”.” Firstly, we just want to point out that the second, three-inch caterpillar looks much different to the first one, so we will treat them as different species. That said, we do think they are both caterpillars.
The first caterpillar is a tussock moth caterpillar. These guys are really quite alien-looking, and are definitely among some of the most interesting caterpillars we have seen before. As they grow older, they also change color quite drastically, though what colors they take on depends on the exact species of tussock moth. The extent to which they can damage the trees that they feed on depends on the number of them. That said, they do not eat “plants down to the dirt”, as they are defoliators, meaning they eat only the leaves of plants. Generally speaking, they are not considered a threat to the health of trees, so we do not recommend killing them. We also do not recommend touching them, as their bristles can cause an allergic reaction, leading to itching and the formation of welts.
The second caterpillar is a forest tent caterpillar. It is actually the most commonly found tent caterpillar species in North America. As opposed to tussock moth caterpillars, these guys do cause more significant damage to the trees they infest. They too are defoliators, but if they come in large enough numbers, their damage can be seen from afar. We recommend our reader check out The University of Florida’s “paper on forest tent caterpillars” for a picture of this, as well as more in-depth information on these caterpillars. While their defoliation does not necessarily kill trees, it can stunt their growth. These guys can also prove to be household pests, as they have been seen climbing up the outside walls of homes to search for a safe place to pupate (the process during which a caterpillar spins a cocoon to metamorphose into a moth or butterfly). Populations are difficult to control, and allergic reactions can occur from touching them as well.
To conclude, our reader found a tussock moth caterpillar and a forest tent caterpillar, both of which are not safe to handle, and which are prevalent defoliators. We do not recommend that our reader kill them, as the most effective form of control, according to The University of Florida’s entomology papers on the respective species, is to let nature run its course. We hope this helps, and we wish our reader the very best!
All About Worms is always free, always reader-supported. Your tips via CashApp, Venmo, or Paypal are appreciated! Receipts will come from ISIPP Publishing.