While a lot of us let our cats or dogs sleep in bed with us, it’s unlikely there is anyone who wants any sort of worm in their bed. Unfortunately, that is exactly the situation that one reader has encountered.
He has found a reddish colored segmented worm on his bed. It is approximately 5mm (~1/5”) long and has a black head with small mandibles. This mystery creature also boasts 6 legs and two small spikes on its rear end. Our reader would like to know what sort of creature it is.
Our first thought is that, considering the spikes, that it could be any number of creatures dressed up for some sort of punk dance night. However, the pictures don’t support this theory, since the spikes seem to be part of the creature and not an accessory. Also, it may be that this is an example of a caterpillar with a split tail and not spikes at all.
Given that it has legs, we can immediately rule out any kind of worm. It looks as though it could be any number of different types of caterpillars.
One likely suspect is the Delias eucharis, or Jezebel Butterfly. The coloring and shape are correct, but it does seem to be lacking spikes or horns of any kind.
One of the things that make the identification of some of these critters is difficult is that many of them go through several different “instars” before reaching maturity. Each time the caterpillar molts, it exits one instar and enters another. Many caterpillars molt their skin several times during their maturation. Since we typically have no idea what instar a caterpillar is in when we get a picture, it can be hard to identify what species we’re looking at.
For example, the caterpillar for the monarch butterfly (Danaus plexippus) goes through 5 instars, which all look slightly different. A photographer named Sid Mosdell has captured many of them on film and has been so kind as to make them available to us in an album. (We are able to reproduce these images here via the Creative Commons License 2.0).
In this case, the three instars shown all look quite different, and may resemble other caterpillars more than they resemble one another. This is why we have to give our best, educated guess when identifying species from a picture.
Unfortunately, the picture our reader sent to us could be of any number of caterpillars in one instar or another, and it cannot be positively identified. If he should find other caterpillars later on, hopefully he’ll take a picture and send it to us along with this original. With more data, we may be able to identify the species, or at least narrow it down.