A reader from Australia requested assistance in identifying some worms he’s found in his bathroom. He says that they are 3 mm – 4 mm (0.11” – 0.15”) long, black, and drop from the bathroom ceiling on threads. Once they land, they walk end over end. It is summer in Australia and he says that the temperature is around 40°C (~104°F). He would like to know what they are because they are freaking him out.
We can understand his concern, they certainly sound like an unusual visitor. He was not able to provide us with a photograph, so we’re going to have to do a little detective work here.
First, if the “worms” are spinning threads on which to drop, then these are not worms, they’re larvae. Typically, when we hear about larva that are dropping on threads we think of inch worms (larva from the moth family Geometridae). These are very common, and we’ve written several articles about them. People find them on their walls, in their bedrooms, and in the bathroom. Inchworms come in a variety of colors including grey, brown, and black and are all quite small. They are also, we would like to note, almost universally cute.
An inchworm. Photo by John Anes. (CC BY-SA 2.0)
The only thing between us and a certainty that our reader’s house is home to an inchworm colony is his description of how the “worms” in his bathroom are moving. He describes them as moving “end over end,” which is not a mode of movement we’re familiar with. A quick internet search shows only virtual worms that move in a manner that can be described as “end over end,” though there are spiders that move in a series of cartwheels that could be described that way. However, we found no evidence of any worms or larva that move in such a way. Inchworms do move in a very distinctive way, pulling their rear ends close to their front ends in a recognizable Omega (Ω) shape, but we’re not sure that this would qualify as “end over end”.
Knowing that there are many Australian creatures which are (to we Americans) strange and unusual, we consulted our references to see if there were any critters specific to the Australian continent which move in this manner. We were unable to come up with any specific examples.
Unfortunately, with the information given we’re unable to come up with an identification. Our reader may want to consult the Coffs Harbour Butterfly House, as they specialize in Australian creepy-crawlies.