- These insects are famous for their catastrophic invasions, mentioned even in the Bible as the eighth plague. Locusts are divided in about 10,000 species grouped in 10 families. All plague locusts belong to the family Acrididae.
- It takes approximately two weeks for the fledgling locust to reach sexual maturity. Adults often group together into swarms containing thousands of locusts. Adult locuststypically live about 10 weeks.
- Locusts can jump 70 cm (2.3 ft).This is like humans jumping 18 m (60 ft)!Though they don’t bite intentionally, they have been known to “chew” a person or two during migration or prolonged contact.
- Controlling Locust
The best time to spray locusts is during the nymph stage before they can fly – Once they are airborne control methods become harder and more expensive.
The most commonly used pesticide, fipronil, acts on the locust’s nervous system.
- Toxicity issues
- America’s Environmental Protection Agency(EPA) classifies fipronil as “Group C — possible human carcinogen”, based on increases in thyroid follicular cell tumours in rats in laboratory tests.
- It also warns that it is highly toxic to honeybees.
- The main disadvantage of fipronil, is that it is non-selective, so other animals are affected even though the amount used is small and is not lethal for the mammals, reptiles and birds that feed on the locusts.
- Pesticides v biological controls
- An alternative to pesticides is a biological agent based on a naturally occurring fungus discovered by the CSIRO on dead locusts in central Queensland in 1976 – based on the spores of the metarhizium fungus. Once sprayed onto locusts it attaches and germinates, eventually stopping the insects from feeding and reproducing – it may be slower to act and less effective than pesticides in some regions. It is also far more costly to produce and apply.
In comparison, the metarhizium fungus-based biological agent, is very species specific, and has “no residual impact in the food chain and is non-persistent in the environment, But it may not be completely without risk.
Overly it is a case of risk management and as long as the product instruction labels are followed, the potential risk is reduced to a safe level.
- Other control methods
People in central Africa use physical controls to catch and net locusts, which are then used for stock feed.
Locusts and grasshoppers as food
People in Africa, South America and other areas eat locusts and grasshoppers as food. For example, some Mauritanian pastoralists kill locusts for both food and medicine. They grind them into a powder to eat. They believe that since locusts eat all trees, they must be the cure for all diseases, since there is a tree to cure every sickness.
People wishing to eat locusts and grasshoppers or use them as animal feed have to be careful. If the locusts have been sprayed with chemicals, they can harm you and your animals.