Family Pompilidae
Order Hymenoptera
Spider Wasps (family Pompilidae) are solitary wasps. They prey on spiders to feed their larvae or they parasitise other spider wasps. They do not form colonies to defend nests and are not aggressive.
Spider Wasps are active in gardens during summer months. The Spider Wasp most commonly encountered is Cryptocheilus bicolor. This is a very large (up to 35 mm long) black wasp with orange wings and legs and a broad orange band around its abdomen. It holds its wings up when resting but flicks them when it hops and runs about on its long legs.
Spider wasps are often seen digging in soft sandy soil, dragging huntsman spiders along. The wasps you are most likely to see and hear are female wasps preparing nest chambers for their larvae. They dig a burrow using long spines on their front legs, then search rapidly around tree trunks and on the ground for a spider. The wasp stings the spider to paralyse it, and drags it back to the burrow. She then lays an egg on the spider's body, and seals it in a chamber or cell at the end of the burrow. The larva hatches and feeds on the body of the spider before pupating in a thin silky cocoon in the cell.
Some spider wasps sting the spider and lay an egg on it but do not dig a burrow to put it in. The spider is left where it was stung and the larva hatches and eats the spider.
A small number of Spider Wasps steal spiders from other Spider Wasps for their own larva. This behaviour is known as klepto-parasitism (klepto: Ancient Greek for 'theft').
The females can sting but stings are not common. As they are solitary insects, spider wasps do not pose the same level of threat to humans as social species of bees, ants or wasps do. However, unlike bees, wasps can sting more than once, and do not die after stinging. The sting causes a burning pain and swelling. If stings are multiple, a more severe systemic reaction may occur.
In some individuals, wasp, bee and ant stings can cause an allergic reaction (anaphylaxis), but this is relatively uncommon. Effective treatment is available, which involves known bee/ant/wasp sting allergy sufferers carrying a special kit when outdoors. Immunotherapy or desensitisation is also available, and can reduce the severity of the allergy.
A cold pack may be used to relieve the pain of the sting. If there is evidence of a more severe reaction or the sting victim is known to be allergic to wasp and bee venom, medical attention should be sought immediately.
Copyright © Australian Museum, 2003
This page: http://www.amonline.net.au/factsheets/spider_wasps.htm
