Insects of Southern Australian Broadacre Farming Systems - Grains ...

Lifecycle
Complete metamorphosis.
Wasp parasitoids have a lifecycle that coincides with
their host. The eggs are either injected into the host prey
or attached to the outer body. Larvae feed internally on
a host which is often killed in the process. They either
emerge from the host to pupate (e.g. braconid wasps) or
emerge from the host as adults (e.g. aphid parasitoids).
Different wasp parasitoid species can attack at different
stages of the host’s lifecycle.
Confused with/similar to
These wasps resemble small flies but they are usually
shiny in colour and have two sets of developed wings.
They can be confused with other wasp species, which
are hard to distinguish in the paddock and identification
often requires specialist knowledge.
Evidence of parasitism
in aphids: mummies
Mummies are aphids that have been
transformed into juvenile wasp casings and
are only evident in the later stages of the
wasp’s development.
Look for:
• round, bloated, buff to bronzed coloured
aphids that are relatively slow moving or
stationary;
• emergence (exit hole) in mummies;
• aphid skin casts - don’t confuse these
with mummies or aphids.
Distribution/habitat
Common throughout most of Australia and can be found
in a variety of habitats. Due to their close association
with their host, their distribution is usually similar to that
of their host.
Insects of Southern Australian Broadacre Farming Systems Identification Manual and Education Resource © 2012
Pests attacked/impact on pests
Ichneumonids and braconids attack a range of insects
(mainly the larval form) where the developing wasp
larvae can grow either inside the host (endoparasite) or
externally on the outside of the host (ectoparasite).
Ichneumonid wasps inject their eggs into native
budworm or armyworm pupae within the soil. The
feeding larvae prevents the moth from emerging,
reducing future generations of pests.
Braconids attack a range of caterpillar pests including
armyworm, cutworm and budworm. They lay their
eggs inside host caterpillars which are often < 10 mm
in size. Developing wasp larvae feed internally, before
burrowing through the skin of their host and spinning a
silken cocoon externally.
Many species are utilised as biological control agents
of pest insects as they have a small host range - where
a particular wasp attacks only one or several closely
related genera.
Some particular species include:
Netelia producta attacks native budworms and other
noctuid moths.
Diadegma semiclausum and Diadromus collaris attack
diamondback moth larvae.
Ute Guides, Southern (pp. 123-125,127)/Western (pp.98,99,102,103).
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SECTION 4 COMMON Pest, Beneficial and exotic Species
Evidence of parasitism
in some caterpillars:
external wasp cocoons
Some wasp species will:
• leave emergence (exit) holes in the
caterpillar host and spin a cocoon nearby;
• pupate inside the host, resulting in the
host pupae differing in some way (e.g.
changing colour or shape).