We received a picture of a larva in a man’s hand. The man would like to know what type of larva it is. He says that he has looked over the All About Worms site, but has not found the information he’s looking for.
To us, it looks as though he has found a warehouse beetle larva (or Trogoderma variabile), though it is difficult to be certain. This is a relatively clear photograph, and our reader may be frustrated that we cannot offer a more definite identification.
There is a reason that, historically, the most reliable way to identify various beetle and fly larvae is to let them grow up and see what sort of animal they grow into. The differences in the larval stage of different species can be quite subtle. Additionally, the larva of a single species can vary in appearance depending on its age.
Also, the traits that we would use to more positively identify a larva are often difficult to see in person because the larva are so small, and can be very difficult to see in the photographs we receive. To us, the larva in the photograph could be any of the species below.
Looking at these photographs, it seems clear that these are not the same species. Clearly, each of these species have distinguishing characteristics, such as the number of legs, types of hair, and mandibles. But, most photographs are not detailed enough to allows us to see those characteristics. So, imagine that each of the photographs above is much smaller, showing significantly less detail. Suddenly, they all start looking more alike. That is why we so often state that a photograph might be this or that species, instead of giving a definite identification.
The more clues we get, the more definite we will be able to be in our assessment. For example, knowing the geographic area, as well as the specific location (in a house, outside, in the pantry, etc.) in which the larva was found will help us to narrow down the options. Given that information, we’re going to try to narrow down the options to the most likely species. In this case, we’re putting our money on a warehouse beetle larva. Though, since these typically live in grains, this may be an unusual creature to find inside a house.