PEST

NAME
Grasshoppers and Locusts
Various Grasshopper Species

ORDER
Orthoptera


Description of the Pest
Grasshoppers and locusts are simular but varying in colour. Grasshoppersare a solitary insect while Locuststend to feed in swarms that vary in size from season to season, depending on climatic conditions. Generally there are two types of insect, one with antennae that are longer than its body (long-horned grasshopper) and are regarded as a solitary feeder. The other insects have short antenna and are known as (short-horned grasshopper) and include species that swarm, examples are below.

The adults may be winged, short-winged with the forewing thicker forming a cover when at rest, or wingless. Some male species can produce sound from special forewings, abdomen and hind legs. They all have enlarged hind legs designed for jumping and are usually well camouflaged.
Nymphs are simular to the adults but smaller and wingless, both have chewing mouthparts.

     

Australian Plague Locust(Chortoicetes terminifera) is a brown adult short-horned grasshopper with females up to 40mm long and has black markings on the transparent hindwings. The smaller male is simular and both are heavy feeders eating large pieces out of leaves. They are found from tropical to temperate zones forming plagues that migrate and consume all that is in its path.

Giant Locust(Valanga irregularis) is a large brownish short-horned grasshopperup to 80mm long with transparent hind wings and the bright green nymphs do not resemble the adults. Both adults and nymphs feed on leaves, eating large pieces and attacking Palms or Hibiscusspecies. Common in tropical and sub tropical regions.

Green Gum Tree Hopper(Torbia perfecta) adult is a long-horned grasshopper up to 50mm long with antennae that grow to 60mm in length and has folded flat wings that resemble a leaf. It is a solitary feeder that is found from sub tropical to temperate regions attacking primarily Eucalyptusspecies.

Katydid (Caedicia olivacea) adult is dark green long-horned grasshopper up to 50mm long and grows antennae to 60mm long. Its wings fold to appear as a leaf and are not easily seen. Commonly a solitary feeder that is found on the coast or inland from sub tropical to temperate regions, and may occur in large numbers feeding primarily on Eucalyptusspecies.

Migratory Locust(Locusta migratoria) is a brown short-horned grasshopper up to 60mm long and is recognisable by the spiny hind legs and strong looking head, but feeds solitary primarily on Palm species, eating large portions of the fronds. It is found in tropical regions but migrates south with the aid of prevailing wind to sub tropical regions, mainly along the coast.

Appearance and Distribution of the Pest
These insects are found in Africa, Australia, North America, Asia, and Southern Europe. They infest areas by hopping at the nymphal stage or flying with the assistance of wind. They tend to prefer inland regions, but are also found on the coast.

     

Life Cycle
These insects have a Hemimetabolouslife cycle, ie. When the immature nymphsresemble the adults.
Generally the adult deposits up to 30 eggs (egg pod) in the soil during spring, summer and autumn with up to two or more generations per year. The emerging nymphs are called hoppers and there is five stages before the wing buds emerge developing into an adult. The eggs overwinter in a dormant state underground emerging during spring.

Period of Activity
The adults appear during the warmer months of the year. In the dryer areas outbreaks are less frequent though in areas of high rainfall, the outbreaks occur frequently and may turn to plagues.

Damage Caused
Grasshoppers and Locusts are very destructive, singularly and especially in swarms which can defoliate entire fields of corn. The host plant has large pieces of its leaves eaten, the bark is nibbled and almost any part of the plant attacked.

Susceptible Plants
A wide range of commercial crops including corn, wheat, and vegetables. Ornamental shrubs, trees or weeds are also attacked. Certain species are a major pest problem for agriculture.

Cultural Control
It is difficult to control but in early mornings the insects are slow and may be caught and squashed. In a large garden or farms, allow the chooks to free range around the vegetables. They are persistent consumers of the insect. Plants may be covered with a net to reduce access for the insect.

BiologicalControl
The adult insect is eaten by many birds, predator bugs, lizards and frogs. This helps control small outbreaks but has little effect on swarms.

Chemical Control
It is difficult to chemically control Grasshoppers and Locusts and must be carried out over a wide area and spraying may not guarantee that the crop is not damaged. Bates or traps may also assist in controlling numbers.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.