The Hymenoptera, insects commonly known as ants, bees, wasps and sawflies, comprise a significant proportion of arthropod diversity in most terrestrial habitats. They are one of the four mega-diverse orders of insects, along with the Coleoptera (beetles), Diptera (flies), and Lepidoptera (moths and butterflies). Over 115,000 species are described worldwide, of which about 11,000 (9.5%) are described from Australia alone. However, the true size of the order might be as much as five times this number. Species of Hymenoptera occur ubiquitously, from forests and woodlands to grasslands and wetlands, freshwater and intertidal zones to urban parks and gardens. Due to the group's diverse biology and ecology no other insect order plays such key roles in the functioning of both natural and agricultural ecosystems. Wasps regulate insect populations though predation and parasitism; bees are among the most important pollinators of flowering plants, and ants dominate many terrestrial landscapes where they are involved in vital ecological processes such as predation, seed dispersal and soil health.
The order is normally divided into two suborders: the Symphyta (sawflies) and the Apocrita (comprising all other groups). The Symphyta is largely a northern hemisphere group and is represented in Australasia by only six of 14 families (of which the Siricidae is introduced) and about 180 species, most of which belong to the Pergidae. The Apocrita makes up the vast majority of hymenopteran species, with 61 families occurring in Australasia, four of which are endemic to the region: Austrocynipidae, Austroniidae, Maamingidae and Peradeniidae. The morphology of apocritan wasps differs markedly from that of the Symphyta: Apocrita have a pronounced constriction or waist between the first and second abdominal segments which clearly divides the apparent thorax from the rest of the abdomen.
The Australasian Hymenoptera are extremely rich in species, particularly the ants (Formicidae), bees (Apidae), wasps belonging to the families Crabronidae, Mutillidae, Pompilidae, Tiphiidae and Vespidae, and the parasitoid superfamilies Chalcidoidea, Ichneumonoidea and Platygastroidea. The superfamily Cynipoidea is noticeably depauparate in Australasia compared with the northern hemisphere where they are a common group of gall inducers on plants. However, in Australasia this niche appears to be largely taken over by members of the Chalcidoidea.
The parasitoid superfamilies are by far the largest in terms of species but overall they are also the poorest studied. They oviposit into or onto the juvenile stages of other insects (as well as other arthropods such as spiders), and the parasitoid larva then feeds on the host to complete its development. This aspect of the biology of parasitic wasps, in conjunction with their often high level of host specificity, has rendered them ideal as biological control agents of a large range of agricultural and horticultural pests.
Further information can be found in Gauld & Bolton 1996, Goulet& Huber 1993, and Naumann 1991.
The following people generously provided help and advice on various groups of Hymenoptera: Jo Berry, Graham Brown, Matt Buffington, Andy Deans, John Early, Mark Harvey, Steve Shattuck, Ken Walker and Alice Wells. We also thank Catherine Harvey for undertaking many of the excellent line drawings, and the following people for allowing us to use their superb images of Hymenoptera to illustrate the key: Geoff Allen, Lyn Bobbin, Roger Burkes, David Hollander, Mike Keller, Mike Lee, Remko Leys, Kym Perry, Andy Reeson, Matt Taylor, Ken Walker, Gerhard Weber, Philip Weinstein and Glenys Wood.
CSIRO Publishing kindly allowed us to use the images of Maaminga, and Melbourne University Press and CSIRO Entomology the line drawing of Austrocynips.
Finally, many thanks to the numerous people who helped us to test the key, enabling us to improve it substantially over earlier versions. They include: Tessa Bradford, Fiona Callaghan, Michelle Guzik, Remko Leys, Amy Macken, Daniel Maidment, Kate Muirhead, Nick Murphy and Simon Ong.
All original images and content in this guide and key are protected by copyright and apart from any use as permitted under the Copyright Act 1968, no part may be reproduced or distributed by any process or stored in any retrieval system or database without prior written permission. Copyright inquiries should be addressed to the Director, Australian Biological Resources Study, GPO Box 787, Canberra, ACT 2601, Australia.