Where do insects go in winter?

Insects are ectothermic meaning they don’t generate their own body heat, and rely on external sources to regulate their body temperature. Freezing temperatures are life threatening to many insects, so how do they survive winter?

One July morning I went down to my vegetable garden to see how the plants had survived the deep freeze (-3°C) of the night before. I wasn’t surprised to find my brassicas were covered in ice crystals, but I didn’t expect to find a cabbage white butterfly (Pieris rapae) larva also encrusted in ice. I decided to keep an eye on it, so after the day warmed up a bit I revisited the garden to find the caterpillar happily munching on the plant. How did it do it?

Cabbage white larva Continue reading Where do insects go in winter?

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Gum tree lerps

As winter sets in there are less and less flying insects to be seen, which might seem like a bad time to be an entomologist. But even in the middle of June there are still plenty of insects around – you just need to know where to look. Personally when I get a bit desperate for hexapodal company I head for the nearest gum tree.

Gum trees (Eucalytpus spp., Corymbia spp and Angophora spp.) are hosts to myriad insects but today I want to talk about the insects which form “lerps” on gum tree leaves. A lerp is the white sugary, waxy covering which the immature stages of some psyllid insects (family Psyllidae) produce from liquid excretions known as honeydew. There is disagreement among scientists as to the purpose of the lerp. Some argue that the lerp is protection from predators, while others insist that it provides the immature psyllid with a more humid environment. Perhaps it is a mixture of both. The image below shows an intact lerp in the upper image and then moved to reveal the Glycaspis sp. nymph underneath.

lerps Continue reading Gum tree lerps

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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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