What is a bug, anyway?

One of my motives for starting Green Path was to document all the small wildlife I was discovering by prowling around my own garden with a camera, that is (to most people) bugs. But what is a bug, anyway, in more formal terms?

orange and black bug
True bug: Horehound Bug (Hemiptera)

If we want to be technical, bugs should really be limited to insects (six legs) so spiders are out. And to be even more technical, entomologists talk about “true bugs” which are a specific family of insects, Hemiptera (the sap-suckers – aphids, shield bugs, plant-hoppers, etc). The obvious implication is that non-Hemipteran insects are not really “bugs”, although I’ve never heard anyone actually say so.

I discussed this profound issue over a beer recently and we decided that all insects except butterflies and moths are bugs. So are millipedes, mites and ticks, which are not insects. Spiders? No, not really bugs, but not insects either. Crabs? Not bugs.

All of the above, however, are invertebrates (i.e. they don’t have backbones) and in fact they are all Arthropods, defined as “invertebrate animals having an exoskeleton (external skeleton), a segmented body, and jointed appendages.”

Mayfly hanging beneath a leaf
Bug: Mayfly (Ephemoptera)

What it all boils down to, I suspect, is that a “bug” is any small arthropod we don’t have a better name for. Frankly, I don’t worry about it too much: if a critter intrigues me or if it’s beautiful, I will want to know more and take a photo.

And “critters” = “creatures” so my scope is even broader than “bugs”. Insects, spiders, crabs, lizards, birds, koalas, people, whales … all critters, all deserving respect and understanding.

wallaby
Critter: Bennett’s Wallaby

I am an ant! Really!

Ant-mimicking Hemipteran nymph uid 5268I lie.

I am not actually an ant at all, but looking like one may save me from critters willing to eat harmless vegetarian bugs like me but unwilling to attack nasty-tasting, big-jawed ants.

Starting again, a bit more seriously: these photos show a couple of insects I found together in my garden recently. The first is about 6mm long, the second about 8mm. My first and only thought was that they were ants, although the transparent rim around their bodies looked strange for an ant (and just as strange for anything else) and so did the bracket-shaped shoulder-piece of the larger one.

Ant-mimicking Hemipteran nymph uid 5253I uploaded both photos to my Flickr photostream and the good people from the Field Guide to Australian Insects and Encyclopedia of Life Images soon put me on the right track: “I’m guessing that these are close to the Broad-headed Bugs (Alydidae). Both seem to be immature stages and the wings have yet to develop completely. The adult would have wings covering the abdomen,” and, “not an ant but an Hemipteran nymph … it vaguely resembles other ant-mimic bugs in the family Nabidae I know from Europe,” and, “Definitely an ant-mimicing heteropteran nymph. We (Aussies) have numerous species spread among several families that have ant mimics as nymphs,” and, “Semi-transparent seams give the impression of several constrictions, where there are none!” (Clicking on the images on this page with take you to Flickr, where you can see the whole discussion as well as full-size photos.)

In this light, the puzzling features weren’t so odd: I know a native cockroach  and a beetle which have transparent edges to their coloured carapaces, and the ‘shoulder-piece’ is simply a pair of wing-buds.

Once the right track, I succeeded with an image search. The best match I found was on Brisbane Insects’ invaluable site, Rhyparochromidae – Seed Bugs, which told me that Rhyparochromidae is a family closely related to Lygaeidae (Seed Bugs, Milkweed Bugs and Chinch Bugs). They are small dull brown or blackish bugs which eat seeds; many of them are flightless.  When (if) my bugs become adults, they should look something like this or this (not my photos), with wing patterns mimicking the ant-like body segmentation.

These bugs are far better ant-mimics than the jumping spiders I found a while ago. Some of their relations are pretty good, too – visit Brisbane Insects’ ant-mimicry page to see them.