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What's bugging Gerry Cassis?

Updated: Mar 22, 2019

Everyone knows something about bugs, right? Or do they?

Gerry (short for Gerasimos) Cassis was born into an emigrant Greek family near Lismore in northern New South Wales. Originally banana farmers, Gerry's family moved into town and opened a deli to supplement the farm income when the banana market crashed in the 1950s. Despite living in town, Gerry continued to spend time on the farm and in the nearby bush, where he started exploring the insect world. This was the beginning of his life's work.

Gerry Cassis at work disovering, describing and classifying new species of bugs

Like many children of migrants, especially after the education reforms of the Whitlam years, Gerry was able to achieve something has parents could only imagine - admission to university. At the University of New South Wales, biology soon became a favourite subject. And it was here that Gerry was bitten by the bug of taxonomy, inspired by a third-year course in entomology. An Honours project working on the taxonomy of the often brightly coloured, iridescent, sap-sucking jewel bugs (family Scutelleridae), which are particularly prominent in the tropics and along the east coast of Australia, confirmed Gerry as a bug man.

Jewel bugs (family Scutelleridae). True bugs undergo "incomplete" metamorphosis - juveniles are similar in size and shape to the adults, but lack developed and functional wings. Other large groups of insects such as flies, beetles, butterflies and wasps have very different juveniles and undergo "complete" metamorphosis via a pupa stage. Notice the two large adults and five wingless juveniles. Colour patterns in jewel bugs vary widely - these are all one species.

As an entomologist, Gerry uses the word "bug" with great taxonomic precision, to refer only to insects of the Order Hemiptera, sometimes called "true bugs". When a non-entomologist uses "bug" to refer to almost any insect (or even non-insects like spiders or millipedes), they're being wildly inaccurate taxonomically.

More than 6,000 of the world's 60,000 named true bugs occur in Australia. But Gerry estimates that over 20,000 distinct species of bugs call Australia home - that is, only around 30% of our species have been discovered and named so far. Bug taxonomists still have a lot of work to do.

The Order Hemiptera is highly diverse and includes familiar insects such as aphids, cicadas, stink bugs and water striders. Any tree or bush anywhere in Australia is almost certainly home to a wide variety of bugs: even an average suburban backyard will be full of bugs, some of which will almost certainly be new to science.

Gerry specialises in plant bugs in the family Miridae, which he started studying for his PhD research at Oregon State University. Unlike the jewel bugs, mirid bugs are mostly small and dull-coloured or green. But, all bugs are fascinating to Gerry, even the dull ones. Some mirids, for example, are adapted to living on plants with sticky surfaces designed to make life difficult for other insects. Some light-bodied species with long, slender legs avoid getting stuck by walking very delicately, while other stronger, stockier species have non-stick surfaces and force their way through or past the sticky hairs of the plants they live on.

Setocoris bugs take all this a step farther. They walk with great care among the deadly, insect-catching hairs of carnivorous plants like sundews (Drosera), feeding on the unluckier insects that have been trapped and eaten by the plant. Very few insects can do that and get away with it!

This Setocoris bug is able to move freely, but very carefully, among the gland-tipped, sticky insect-catching hairs of a Drosera sundew. It feeds on the juices of other insects caught by the sundew, effectively robbing the predator of its prey. Photo: Fred & Jean Hort.

Gerry is considered a world authority on the bugs of Australia. He has worked at CSIRO's Australian National Insect Collection, the Australian Museum and the University of New South Wales. With collaborators and students, he has named more than 500 species and discovered many more that have not yet been named. In one group alone, the Orthotylinae, Gerry's group has increased the number of known Australian species from 50 to more than 2000!

Gerry's research allows him to explore the world. He has collected bugs throughout Australia, Africa, the Americas, Europe, New Caledonia and throughout the Pacific. He works frequently in Papua New Guinea and the Solomon Islands, collecting bugs and training a new generation of entomologists and 'parataxonomists' in the identification and taxonomy of insects.

Gerry with colleagues in Papua New Guinea

Identifying and understanding the biology of bugs is important for many reasons. Some, including assassin bugs and bedbugs, are predators of other insects or feed on mammal (including human) blood. Most, however, suck the sap from plants, and some of these are important crop pests. Pest bugs weaken the plants as they feed, and spread viruses and other pathogens. Bugs are estimated to cost the Australian agriculture many millions of dollars per annum due to pest control and crop losses.

For this reason, Gerry's career has always had an important practical focus. His research has helped in biological control of pests, including using predatory bugs to control other pest insects. His research plays a vital role in biosecurity for Australia and our neighbours. We are currently free of some of the world's worst pest bugs, partly thanks to the expertise of entomologists like Gerry and their love of bugs.

The mirid bug Macrolophus pygmaeus is used to control whiteflies in tomato greenhouses. But when they run out of whiteflies, the bugs are perfectly happy to start feeding on the tomatoes. The pest-killer becomes the pest!

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