Stick Bug Jealousy

In the three years which I have been keeping walking stick insects, I have not noticed any displays of emotion.  In fact, they hardly seem to move - or eat, for that matter.  They don't seem to seek out or mind the attention of other stick bugs.  If one walks on top of another, neither one seems to pay any attention.  With the exception of the adult males, who do manage to seek out and mate with the females.

Last week my daughter brought her small cage of stick bugs to display to the whole school, so the night before, I cleaned out the cage for her, and set up fresh blackberry leaves.  We were a bit concerned to see a male and female joined together, since this sort of thing would raise unnecessary questions from the younger kids.  As I removed the lid which they were clinging to, a second male approached from behind and climbed onto the first (successful) male's back.  I figured it was just because I had disturbed them, and expected them to soon settle.  Instead, I saw something I didn't expect.  The second male appeared to bite the first male on the leg.  The first male recoiled slightly, which confirmed to me that it was actually a bite which I had witnessed.  Then he bit again.

Normally, I would have gone for my Blackberry, to be ready to record in case it happened again.  But it was late at night (which always seems to be the case when I am cleaning their cages), and I wanted to get done before I got too tired.  So I never did see whether the biting continued.  But when I returned the lid a few minutes later, it appeared that the first male was still in position with the female, and the second male was still waiting nearby, perhaps jealously.