Plague Thrip

Thrips imaginis

Family: Thripidae

Order: Thysanoptera

Description:

Dark colour or yellow.

Body - 1.2 mm long and slender with hairs.

Wings (when present) are fringed. They lay parallel to the body when at rest and do not overlap.

Asymmetrical mouthparts for sucking and scraping.

Antennae have 4-9 segments.

Fore legs long and slender and often modified for gripping.

Hind legs larger and modified for jumping.

Abdomen has 11 segments. Spiracles are on segments 1 and 8.

Biology:

Life Cycle:

One to several generations per year. Hatches from a relatively large egg to become a larva, then a pupa that looks like a nymph (or miniature adult). Has several moults before reaching it final size in several weeks. They may be carried long distances by wind. May fly or be blown in the wind. Heavy rainfall and natural enemies help control populations in most years.

They occur in largest numbers in spring and early summer and survive in small numbers over winter. Numbers fall in very hot weather but may increase again in autumn.

On warm days they may swarm in enormous numbers and settle on sheets and woollen clothing left out to dry.

Habitats:

Origin and History:

An Australian native insect.

Distribution:

Significance:

DAMAGE

They feed on pollen and flowers. This may prevent fruit set in apples, pears and stone fruit, or cause premature browning of cut flowers. Tomatoes, strawberries, grapevines and beans may also be attacked. They occur in plague proportions in some years and may be rare in others.

Some people show an allergic temporary skin rash reaction after contact with thrips.

Management and Control:

In most years control is not economical. A number of insecticides can be used in plague years but early application before flowers open is necessary.

Related Species:

Similar Species:

References:

CSIRO. The Insects of Australia. Melbourne University Press. (1991).

Jones, D. & Elliot, R. Pests Diseases and Ailments of Australian Plants. Lothian Publishing Co. p182.

ICI Technical Manual p28.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.