Ant mimicking bugs suck!
Back in 2008 in North Queensland, Australia I stumbled upon a common Green Tree Ant (Oecophylla smaragdina) but this one was not behaving normally, instead of hanging about with its colleagues nearby it was on its own. Looking at it more closely revealed it was not actually an ant at all, rather an ant-mimicking bug! So what’s the difference? Aren’t ants bugs too?
Well first of all, the term ‘bug’ is generously applied to practically any animal with more than six jointed legs. In scientific terms, the word ‘bug’ should only be used for insects that have sucking mouthparts, kind of like a straw. They all belong to the group Hemiptera or ‘half winged’ insects. Ants belong to another group, the Hymenoptera or ‘membrane winged’ group. This also includes wasps, bees and the wasp-like Sawflies.
Why imitate an ant?
With that cleared up, what would a bug want to look like an ant for? Well, as you can see, the detail is striking. The colours are exact and the wings even follow the contours of the body, the main difference is the straw-like mouthpart tucked up underneath. The basic advantages to looking like an ant include mostly defence. Many ants taste terrible, the formic acids in their abdomens can be very pungent and most predators ignore them. Also, many ants have a powerful bite and sting which also makes them unappealing. Finally, ants are often found in large numbers, where there is one there is often a whole army nearby.
So the ant-mimicking bug can feed in peace. What does it feed on? Many ant-mimicking bugs like it that imitate other ant species are vegetarian, sucking away at flower buds and fresh shoots. This one might just do the same.
Bugs aren’t the only critters that imitate ants… A whole group of jumping spiders do the same. This is not an ant, but a spider. But wait… Don’t spiders have eight legs rather than the six that insects have? Also, what about the antennae, or feelers that insects have but spiders do not? Well, this spider solves the problem easily, by holding up its front legs to look like antennae. It waves them about just like a real ant! Another problem is that ants have three sections to the body- the head, thorax (middle part) and abdomen (rear section).
Spiders have just two, the cephalothorax (head and middle) and the abdomen. This spider has an artificial thorax, formed by a little ‘pinch’ half way down.
Unlike the bug above, this ant mimics Spiny Ants from the Polyrachis group. Jumping spiders that imitate ants apparently feed on them, using their disguise to creep up and launch a lightning fast attack on their unsuspecting victims. The disguise also saves them from spider-hunting wasps that seek out spiders, sting them and take the paralysed body back to feed their young.
Because ants are so common, it makes sense to imitate them.