PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
ORDER ODONATA
Dragonflies, damselflies
NO. SPECIES
IN AUSTRALIA
SOME
DISTINCTIVE
FEATURES
Do not confuse
with:
Damsel bugs
which have a
sucking beak
(also predatory)
or
Flies which only
have 1 pair of
wings
LIFE CYCLE
More than 300 species in Australia. As both adults and nymphs eat large numbers
of mosquitoes and other insects, they are considered to be beneficial insects.
Nymphs and adults are eaten by fish, frogs, birds and platypuses. Some are
endangered, eg giant dragonfly (Petalura sp.).
www.ento.csiro.au/education/insects/odonata.html
Lucid Key: Dragonflies of the World www.lucidcentral.com/
Theischinger, G. and Hawking, J. 2006. The Complete Field Guide to Dragonflies
of Australia. CSIRO Publishing.
ADULT Body 1. Long slender bodies up to 7.5 cm long. about 15cm long.
2. Abdomen long, slender, cylindrical and soft.
3. Short legs.
4. Dragonflies – Internal gills.
Damselflies – Have 3 leaf-like gills for extracting oxygen
at the tip of the abdomen. More colorful
bodies than dragonflies.
Head
Wings
1. Two large compound eyes on the side of the head.
2. Three simple eyes (ocelli) between the compound eyes. The
simple eyes assist in stabilizing their flight.
3. Very small antennae.
1. Two pairs long rigid membranous wings of similar shape
and size.
Dragonflies – Hind wings slightly broader than forewings.
Wings held horizontally when at rest.
Damselflies – Fore and hind wings about the same size.
Wings held vertically when at rest.
2. Strong fliers, in fact they are aeronautical marvels, no small
aircraft can surpass them.
NYMPH Aquatic (fresh water). Only slightly similar to wingless adult, with
mouthparts specially modified for catching prey. Adults are commonly
found near fresh water though some roam far afield.
There is a gradual metamorphosis - egg, nymph (several stages) and adult
with 1 to several generations each year depending on the species.
Dragonfly
Some
variations, eg
nymphs of some
species in Qld
have been
recorded as
being terrestrial,
some dragonflies
in Carnarvon in WA
lay eggs in young
stems of
French beans
METHOD OF
FEEDING
ADULT
NYMPH
All stages have chewing mouthparts. Adults are aerial predators
while nymphs are aquatic predators.
196 Insects and allied pests - Order Odonata (dragonflies)