Predatory Bugs 2 Assassin Bugs

Predatory bugs 2: Assassin Bugs factsheet PDF version (117kb)

Number 12
Revised April 1993
By Charlma Phillips, Principal Forest Health Scientist

Assassin bugs belong to the family Reduviidae. They are medium to large predatory bugs which have mouthparts adapted for piercing and sucking. They are usually solitary insects and are often very conspicuous on the tree, sitting near the tips of shoots, waiting for other insects to come within reach. Both adult and nymphal stages are predatory.

The larger species are capable of inflicting a painful "bite" and may eject a harmful defensive fluid if handled.

There are many different species. Most are regarded as beneficial insects, for example Coranus trabeatus, a very ferocious insect which feeds on a wide range of insect pests. However, assassin bugs will kill and eat any insect they can catch, including other beneficial insects. For example Pristhesancus plagipennis feeds on bees and is thus not regarded as beneficial!

Description

Assassin bugs are medium to large bugs (1-2cm in length) and have a characteristic narrow head with large eyes and a short, three segmented, curved beak or proboscis. The top surface of the abdomen is often concave and the femur of each foreleg may be enlarged or modified to help grasp and hold prey.

Adult assassin bug with small head and curved beak or proboscis.

They are often dull black or brown in colour with red or orange stripes or markings.

The young (nymphs) resemble the adults but do not have wings.

Life history

No detailed studies have been made of the life history of assassin bugs. However, it is known that the eggs are laid in a cluster, glued on to the leaf surface. Soon after hatching, the nymphs disperse to search for food.

Habits

Assassin bugs have toxic saliva which rapidly kills their prey and they then feed by sucking out the body contents of the prey insect. They seem to prefer soft bodied insects such as caterpillars.

Assassin bugs, although active, move relatively slowly and are not easily disturbed.

Adult assassin bug feeding 
Adult assassin bug feeding

Head of an assassin bug showing curved, three segmented beak or proboscis. 
Head of an assassin bug showing curved, three segmented beak or proboscis

Summary

When to look

Throughout the summer months, through into autumn.

Where to look

On leaves and the tips of shoots.

What to look for

Look for large bugs with a narrow head and a strong, curved beak or proboscis.

NOTE: Many Assassin bugs are beneficial.
 

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