Ptilocnemus lemur - the ant assassin
Yes! Finally! We were really quite lucky (and very excited) to witness this act of ant assassination. Jason and I decided to head out on a whim last week, just before sunset. We walked until it got dark and the very first spot where I left the track, I was confronted with a fantastic natural history scene unfolding before my very eyes!
The Camponotus worker that is very much dead here, having been precisely struck in the back of the head, was actually tugging on and pulling along the assassin bug when I found them. Now, you can imagine how quickly I tried to get my camera out of my bag and get it set up. But of course, I could not take my eyes off what was happening on this tree trunk. I didn't even have batteries in my flash and ended up dropping one of the batteries in my mad rush. The next thing I know, the assassin bug has the ant by the head, and is shaking it violently from side to side, as it pierces the weak point between its head and thorax - I missed the switch! Anyway, I finally got my gear together and began snapping away, while ranting on randomly to Jason about how awesome it was to finally witness the assassin make a kill and how random and lucky it was that the first place we stopped happened to show us this. This was my favourite shot of the kill, but I may upload a couple more that were taken at a higher magnification. I rotated this shot 90° anti-clockwise, but am not sure if I prefer it like this.
Now, it is interesting to note that these bugs continue to utilise their leg waving behaviour at night, even though (I assume) the ants cannot see it. There were a few other P. lemur bugs hanging about on this tree (they seem to prefer the thick and tessellated bark of Marri trees than the smooth bark of other Eucalypts) - all sitting in cracks between sections of bark, occasionally moving about, presumably to find a better ambush site. At night, like other nocturnal assassin bugs, they probably rely mostly on ambush to catch ants rather than attracting them with their leg waving. However, I am sure their "trichome" and associated glands still help to attract the ants.
When I was watching the above scene unfold, it looked to me as if the Camponotus ant was dragging the P. lemur bug along by the ventral thorax or abdomen - if this was because the bug had enticed the ant with pheromones from its trichome or not, I am not sure. It could have just been that the ant had captured live prey as a result of random foraging. Nonetheless, the P. lemur was happy to play along with this until the ant was in a favourable position to be attacked. it must be a very risky business, though. I was annoyed that I missed the precise moment the assassin bug went for the kill, but I imagine that it just requires that the head of the ant is placed well enough under its body so that it can stab the weak point behind the head with its rostrum.