Recently, we received several amazing photographs of a couple of creatures. Our reader, who submitted them, says that he found them in his laundry room. He describes them as caterpillars or larvae that are about 1/2” (~1.25cm) long. He would like us to help him identify their species.
Identifying larvae and caterpillars is notoriously difficult. This is because all larvae change appearance as they move from one instar to another. Also, many species’ larvae look alike. So, two larvae of different species may look more alike than two larvae of the same species in different instars.
Many larvae are fussy eaters, so it is often easiest to identify a caterpillar or larva by its eating habits. However, we do not know of any larvae that eat laundry, so that method will not help us in this particular case. Historically, the best way to identify a caterpillar or larva is to catch it and let it grow up. Then, we can see what it becomes once it is an adult. That is not always possible, so we do our best to make identifications from the information we are given.
Our reader’s visitors resemble any number of moth caterpillars. They remind us most of cabbage moth caterpillars (Mamestra brassicae) and Kawakawa moth caterpillars (Cleora scriptaria). Mamestra brassicae are found primarily in Europe, Russia, and Japan and love to eat cabbage and other leafy greens. Cleora scriptaria are found in New Zealand and can be found munching the leaves of the Kawakawa plant. However, both of these species quickly grow much larger than the critters in the reader’s pictures, and neither is commonly found indoors.
The brown larva also resembles the black soldier fly larvae (Hermetia illucens). These are composting worms and can be found chowing down on decomposing plant materials. If these are soldier fly larvae, then the size is about right for a mature larva.
No matter what the species, these critters are unlikely to cause any issues for our reader. In fact, it is the larvae that should be worried! It is likely that these larvae are lost and looking for a way home. Whatever they eat, they are unlikely to find it in our reader’s laundry room. It is likely that they got tracked in on someone’s clothes or shoes and would like nothing better than to go home. We recommend that he move any larvae he finds outside where they will have a fighting chance at finding food.