Insect Architects

After a few months off for house painting one minute bugs is back!

I was prompted to write this post after completing an article for Hort Journal Australia on a similar topic. My argument in the Hort Journal piece was that insects are not mathematical or engineering geniuses, and that their behaviour is dictated by the instincts they have evolved with. All very scientific and anti-anthropomorphic. The post here is a bit different. Let’s marvel at the exquisite perfection of some of the structures that insects build.

Our first architects are moths of the family Psychidae – the case moths. These are harmless creatures found in most gardens throughout Australia. Cases are spun by caterpillars from silk to which twigs, sand, moss, lichen, leaves or bark are attached. The cases can open and close at each end, the front end for feeding and the rear end for ejecting droppings. I believe the species illustrated below is Lepidoscia arctiella – look at how precise those little bits of twig are!

Psychidae

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Cuckoos & cleptos

Most of us are familiar with the activities of avian cuckoos where a bird lays its eggs in the nest of a host bird of a different species, after kicking out the eggs that were laid by the host. We have a dozen or so species of cuckoos in Australia and some of them utilise the nests of birds half their size. The worst mismatch I have seen was a pair of exhausted Superb Blue Wrens (Malurus cyaneus) trying to feed a massive fledgling Fan-tailed cuckoo (Cuculua pyrrhophanus). The young cuckoo was never happy with the amount of food brought to it and constantly pecked its foster parents.

Did you know there are insect cuckoos too? Granted there’s not a lot of the bullying going on like in the bird example described above, but there is certainly similar amounts of clandestine behaviour. There are about 75 species in the wasp family Chrysididae in Australia, with common species being referred to as “cuckoo wasps”. They vary in length from about 6 mm to 22 mm in length and they are strikingly beautiful insects because of their metallic colours.

Chrysididae Continue reading Cuckoos & cleptos

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I love parasitoids

To most people the word “parasite” conjures up all sorts of images from tapeworms to brain-eating amoebas to scenes from the film Alien. So a “parasitic wasp” must be something really freaky and horrible then? To us – no; but to an aphid or a caterpillar or some other target insect – yes.

Technically a parasitic wasp isn’t a parasite at all. True parasites like tapeworms don’t normally kill their hosts, because that would mean their own death. So insects such as parasitic wasps and flies which parasitise and kill other insects are known as parasitoids.

parasitoid Continue reading I love parasitoids

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Revenge of the Mummy

Have you noticed swollen bronze-coloured aphids on your plants? These are aphid ‘mummies’ caused by the parasitic wasp Aphidius of the wasp family Braconidae. There are several species of Aphidius which have been released in Australia. A species that has established well and is common in urban gardens is Aphidius rosae, a successful parasite of the rose aphid Macrosiphum rosae.

Aphidius wasps are shiny black, slender insects about 3 mm in length with long antennae. The diminutive size of these wasps makes it hard to see them in gardens, but you will see the results of their life cycle within aphids. Adult female wasps lay their eggs singly inside adult aphids and aphid nymphs. To accomplish this a female wasp must bend her abdomen under her legs and inject an egg into the aphid with her ovipositor (‘stinger’). If you were watching and you blinked, you would miss it, as this operation takes less than a second. Obviously I don’t have many images like this one.

Aphidius Continue reading Revenge of the Mummy

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