I found another Canifa larva yesterday under red oak bark and I observed behavior that may contribute to an understanding of the function of the fleshy trailing lobe or "caboose" as I call it. I think it is used as a defensive decoy that a predator can attack, at which point the larva decouples from its caboose and makes its escape.

I had collected the present larva under bark of cordwood from the same tree in which I found another Canifa larva that lost its caboose and has since matured. I put it into my ever-present plastic pocket vial along with some other larvae and adult beetles (diaper*ine tenebrion*ids plus one weev*il), dumping all out into a white plastic bowl so they could be transferred sans debris into the deli container I use to shoot live specimens inside my light arena setup. (I make tranfers of small specimens with a wet fine-tipped watercolor brush. The surface tension of the water makes them cling to the bristles.)

The little canifa lay practically motionless except for an occasional feeble twitch, as if it were injured. It continued to behave in the same fashion on the floor of the deli container in my light arena. Viewing its magnified image through my camera I soon saw what the twitching was about. The front half of the larvae remained stock still while the back half moved, especially the fleshy appendage hanging off the end of the abdomen. The larva raised this terminal tip, turning it slowly like a rearing head. It reminded me immediately of some blunt-tailed snakes (Rubber Boa is one example) that hide their real head beneath their coils when threatened and rear their blunt tail as if it were a head. Supposedly the aim is to make the predator grab the decoy head, at which point the snake may spring into action, attacking the occupied aggressor with the real head.

It struck me that Canifa larvae have a somewhat similar strategy. For one thing, their fleshy caboose is lighter in color than the rest of the body, therefore more easily seen, especially when it is moving and the rest of the body is motionless. As such, it is more likely to be targeted by a predator. At first I thought it might be loaded with foul-tasting chemicals that would make a predator lose interest after the first bite. But then I thought of how apparently easy it is for Canifa larvae to decouple from their caboose and figured their decoy strategy might be more like that of blue-tailed skinks (lizards) whose brightly colored tails can be pounced on by a predator, at which point they detach and wiggle wildly about, allowing the skink to escape with a shorter tail that soon begins to regenerate.

Although two other Canifa larvae I found did not exhibit this type of apparently defensive behavior, one had been collected in my pocket vial by itself and the other, which had possessed its caboose going into a well-populated vial, came out with caboose missing. In one case the larva was not threatened by the presence of other arthropods and in the other case, though perhaps threatened, the larva had detached from its caboose so that no decoy ploy would have been possible. In the case of the present larva, after being trampled by other specimens in my vial I speculate that it went into its defensive reflex.

Research projects: Attack a Canifa larva's caboose with forceps or a needle and see if it detaches. Remove the caboose and see if it regenerates. Remove the caboose and see if a hungry ground beetle will devour it (the taste test).

(The rule marks seen here designate half-millimeters.)