Millipede Invasion

Oxidus gracilis Greenhouse millipede

This species has apparently entered the US from Japan, possibly on bark mulch. It first became established in southern states and has subsequently moved North. Around my house, this species has pushed out another small species of millipede which does not exhibit the gregarious behavior.

Some images I have taken are shown below. Apparently there are some predators of this millipede.

picture of pavement ant biting millipedeFig 1 ant biting millipede

picture of pavement ants biting millipedeFig 2 ants biting millipede

Fig. 1 and Fig. 2 Show pavement antswhich have removed legs from this millipede and are attempting to cut it up for transport.

Picture of millipedes mating

Fig. 3 Mating Behavior with male on top of female

Mating seems to take place during the months of July and August, at which time, swarms of this millipede can be seen climbing on the exterior walls of homes, on sidewalks and in the grass. They are not dangerous to people but they release one or more odiferous chemicals when handled or otherwise disturbed. Weather seems to play a part in this behavior. In 2007, we had a long dry spell. The millipedes in my area did not swarm until we received a day of rain. They stopped a week later, only to return after another rain. Individuals were observable well into late August where previously, they disappeared the first week of August.

One observation I made by accident when I first discovered this species is described below.

I captured several individual millipedes and placed them in a container to get a closer look at them. I then set the container off to the side and picked up a young gerbil, within a minute after handling the millipedes. I was in the process of training the gerbil to not bite a handler. Within seconds of touching the gerbil, the gerbil started to rapidly wipe its paws and face. Then it fell to its side and went into a kind of spasm with mouth open and legs stretched out. It took several minutes to recover with no apparent ill affects. I washed my hands and picked up the gerbil a second time. No response this time.

If you handle this millipede, cleanup before doing anything else that might get the substances near your eyes and mouth.

One paper has an analysis of the chemicals secreted by the millipede, which might be interesting reading.

Identification of secretory compounds from the millipede, Oxidus gracilis C. L. Koch (Polydesmida: Paradoxosomatidae) and their variation in different habitats.

Junsei Taira(1), Kazuyo Nakamura(1), and Yoshiko Higa(2)