Eric McCrum, past President and active member of the Darling Range Branch, presented a talk on grasshoppers entitled ‘The bizarre world of grasshoppers’.
Eric’s talk was well illustrated from his extensive collection of slides, a selection of which showed the wide morphology and colourful varieties of grasshoppers from WA.
Eric began with a summary of the essential general body form of grasshoppers and explained that they are a primitive insect group. Their eggs hatch into miniature grasshoppers (nymphs) in contrast to some other insects that have developmental stages involving metamorphoses prior to maturity. Young grasshoppers shed their skins a number of times and initially lack wings (when they are called hoppers); however their essential body form is recognizable throughout their life cycle. The number of moults varies between species. Grasshoppers, crickets and katydids are all members of the Order Orthoptera and it was emphasised that they are many unnamed species in WA.
Grasshoppers live only for a year, dying in winter; the action of ‘flying’ and general physical activities involved in living and feeding eventually damage the wings, making the adults vulnerable to predation. However, the eggs survive through the cold season to a new generation.
General characteristics of grasshoppers are very variable but certain features can be indicative of lifestyle, such as short antennae – an indication that the insect feeds on grasses in the daytime. Many long-horned grasshoppers tend to be more omnivorous. Most grasshoppers are vegetarians, although some are scavengers and others predate, with caterpillars and cockroaches being among the victims. Grasshoppers themselves are victims to many other insects such as wasps as well as birds and animals.
The major groups of grasshoppers are designated by several body characteristics such as the number of segments in the antennae, differences in the structure of the feet, wing structure and veining in the wings. Eric introduced us to eight of the thirteen families and briefly explained some of the major characteristics of each. Examples include ‘ridgebacks’ or gumleaf eaters of the Gonidaea species that shed their skins four times and are themselves often wasp-food. A fine example of a pink coloured Casedicia sp. showed the variation from the usual green and brown colours: this species feeds on cockroaches. Species of Acrididae with an unusual conical head are an example of more bizarre body forms. Also illustrated were a selection showing: colourful crested yellow and green species from the Pilbara and Murchison areas; Monistria sp., a spotted form with vestigial wings from Two Peoples Bay; and sandgropers – an odd form (family Cylindrachetidae) related to grasshoppers, with its front parts formed as shovels. These insects live a subterranean existence feeding on the roots of plants at depths up to 1.5m. Five of the seven of this species are found in W.A., with the only other two species being found in widely separate places; Papua New Guinea and Patagonia.
A common attitude seen in several slides was the attention the grasshoppers give to cleaning their antennae with their feet, and a noticeable number of female grasshoppers displaying conspicuous ovipositors.
The variety of grasshoppers shown through the presentation clearly demonstrated that ‘not all grasshoppers are green’ and that their size, shape, colour, and general body morphology are widely varied. Colour and camouflage are especially well adapted to varied environments, with several photographs showing how difficult it can be to spot a well-camouflaged grasshopper on bark, lichen or in leaf litter, or when cryptically imitating both green leaves and stalks of certain plants. The translucency of some body parts assists this effect.
Eric’s slides represent many years of patient insect watching and the talk was well received by a well-attended meeting. A lively question time followed.
Susan Stöcklmayer