Download 3a Hints on Identifying Insects

Presenter: Dr Christine Lambkin - Senior Curator (Entomology)
Topic:
Hints on Identifying Insects
Now that you’ve collected your insects, we’re going to show you a few methods of how to identify them.
We have, at the museum, developed a few resources that can help you in this regard and many of them
are outlined in our leader’s guide and our user’s guide.
The first thing we have to know is actually what makes an insect or what makes an invertebrate. And the
second thing we have to realise is that many Australian insects are actually not identified. So therefore
they actually don’t have a scientific name as yet; we haven’t got around to identifying them.
An arthropod is something that has an exoskeleton. It’s basically got its hard parts on the outside and
its squishy bits in the middle. There are four major groups of arthropods as you can see here. So the
insects have six legs; they have two antennae; and they have three body regions. In comparison, the
spiders which belong to the Arachnida have eight legs and never have antennae. So that’s one of the
ways that you can tell the difference between those two particular groups.
One of the questions quite often is ‘does your insect or invertebrate have wings?’ If you’re looking from
the top of the body of the insect and you can’t see these segments going across the abdomen, then you
definitely have an insect that has wings but what it’s done is it’s folded its wings over its abdomen and
you can’t see those segments.
Another question you’re quite often asked is about the mouthparts of your insect and to do that you
actually have to turn the insect over and look on the underside of the head. So that’s another thing that
you really have to do and for this I really do encourage that you are dealing with dead, preserved
insects. Don’t try to do this with a live insect. The chances are that you will be either bitten or stung. So
insects bite with their mouthparts and they sting with their abdominal end: the end of the abdomen.
Insects actually have: a head which contains the antennae and the eyes and the mouthparts underneath
as we said; a thorax which has three pairs of legs and has, on occasion, two pairs or four wings; and
then the abdomen is made up of segments - between five and thirteen segments – and it’s usually used
mainly for digestion and reproduction.
The other thing you’ve got to realise is that you can often only identify insects when they are adults. So
many insects go through this complete change that we sometimes call abrupt metamorphosis or
complete metamorphosis.
Beetles can be recognised because they have a straight line down the middle of the back as you see
here. In fact what beetles have done is that their front wings have become extremely hardened and they
cover the abdomen and the hind wings are folded up underneath until they want to fly. They raise those
front hard covers that we call elytra, unfold the hind wings, and then they fly only with the hind wings.
The other group of insects have a different type of life cycle. They don’t have a huge change. They have
a gradual change through their life. Now the ones on the right there are true bugs. Not all insects are
bugs. There is actually a specific group of insects that are bugs or true bugs or sucking bugs and we call
them that because they have mouthparts that have formed a thin straight tube that lies down between
the front pair of legs. That group, if you encounter them, can hurt you a great deal. You try to hold
insects from the top and only when they are already dead and preserved.
November 2010
QM Transcript of Hints on Identifying Insects 1/1