Parasitic Wasp (Ichneumon sp.)
Structure, Appearance and Characteristics
Usually orange-red body with blue wings.
Antennae generally long and multisegmented.
Pedicel relatively large.
Basal half of gaster (abdomen) orange.
Apical half of gaster is black banded with white.
Some species are sexually dimorphic.
Complete metamorphosis (egg – larva – pupa – adult). Eggs laid on host larvae. Commonly parasitise larvae of lawn grubs (eg. Spodoptera spp., Herpetogramma spp.)Female can lay up to several thousand eggs on host. Pupation can occur within host's own habitat (pupation chamber or feeding recess), under bark, in litter or exposed on vegetation.
Prefers habitats with high humidity. In drier areas are more abundant along streams or during seasons of greater moisture.
Being parasites the larva feed on the host itself until pupation occurs. On emerging from the cocoon there appears to be no evidence of further feeding.
Beneficial because of parasitic nature, attacking other pest of man (eg. lawn grubs). People become concerned when these wasps are observed hovering over lawns, thinking that these wasps are laying eggs in the lawns and are the source of lawn grub infestation. Adults do not sting and larvae are parasites of lawn grubs so neither are considered pests.
Strengths include being able to travel long distances in search of hosts, lay large amounts of eggs on host, good fliers. Weakness includes a limited, selective food source and susceptible to insecticides used to control their hosts (lawn grubs). Control measures should not be implemented against these wasps since they perform a biological control function against the lawn grubs.