Caterpillar Pests?

How do I get rid of Caterpillar pests?

Don Herbison-Evans ( donherbisonevans@yahoo.com )
&
Stella Crossley

(updated 28 June 2007)

In the house:

If the caterpillars are walking about in the home, you need to work out if they are feeding there or are invading from outside. If there are similar caterpillars outside, then they are probably invading, and you will have to take more precautions about allowing insects entry to the house: fit screen to all windows and doors, and ensure that the screens are a good fit, and that they are always in use if a window or door is open. If they are feeding in the house you need to find the food they have been feeding on and discard it. Take it somewhere from which they are are unlikely to return, for instance in the garden for the birds to enjoy. Common sources of caterpillars are flour or cereal or dried fruit, being kept in unsealed containers. Our advice is never to keep food stuffs in unsealed containers. If the caterpillars are in textiles like a carpet, spraying with insecticide may be only solution. If in a wardrobe, keep an insecticidal tab in there, and keep the doors closed.

On a house plant: Lift the caterpillars off and take them outside and put them on a plant of the same family if possible. Only kill them as a last resort as this disturbs the balance of nature with the various other species that prey on and control the caterpillar. The hairs on some caterpillars can cause an allegic reaction, so it may be wise to use forceps or gloves to avoid direct skin contact with the beasties. Some caterpillars live at the base of the plant and crawl upwards to feed at night. Therefore inspect the plant in daylight and later at night in darkness.

In the garden: This same method is useful for a few small plants. For a large bed, put sacking along between the rows. The caterpillars will shelter there and can be caught.

On a large plant such as a tree: Ignore them. If the tree is healthy, the caterpillars will cause little more damage than the tree would suffer from pruning anyway. In succeeding years, the build up of the pest caterpillars will allow their parasites and predators to build up their populations and control the pest.

In the lawn and pasture: This is difficult. You could go around collecting them into a bucket, or if you have a big lawn, you could run over it with a heavy roller. Some lawn pests are nocturnal. Try collecting/rolling around midnight, or leave out some sacking for them to hide under by day where you can collect them. Armyworms have been controlled by digging a ditch in front of them, as they then find the extensive section of loose soil too difficult to scale.

In fruit on a fruit tree: Once the fruit are attacked it is too late to protect the fruit. Knowledge of the life cycle of the caterpillar is necessary to prevent infestation. Some species lay their eggs on the flower, and they hatch only when the fruit is well developed. If the female moth is flightless, she can be prevented from reaching the flowers or fruit by wrapping a sticky band around the tree. Sticky bands are also used to prevent caterpillars from reaching the soil where they pupate. Stretching netting over the trees that are susceptible to attack can be used to stop moths also. These methods can be found in books on growing fruit.

Borers in trunks and branches: The only hope to save a particular tree is to inject it with a systemic insecticide: bore a thin hole in the trunk and inject a systemic insecticide with an eyedropper. Borers are a big problem in Australian trees and shrubs. Most native shrubs in Australia have their lives limited to about 10 yrs because of borers. The long term solution is to keep planting young replacements every 5 years so that there are mature plants on a rotating basis.

On farms and nurseries: We do not advise using insecticides because not only do they kill the caterpillars but they also kill their natural predators, such as those listed below. This means that in subsequent years, the problem will probably get worse. Long term solutions are biological: finding other organisms that attack the particular pest caterpillar species. These can include :

viruses such as Cypovirus ( REOVIRIDAE ),

bacteria such as Bacillus thuringiensis ( BACILLACEAE ),

imperfect fungi such as Beauveria bassiana ( MONILIACEAE ),

nematodes such as Neoaplectana bibionis ( STEINERNEMATIDAE ),

lacewings such as Chrysopa perla ( CHRYSOPIDAE ),

daddy-long-legs such as Phalangium opilio ( PHALANGIIDAE ),

ant-like flower beetles such as Anthicus cervinus ( ANTHICIDAE ),

beetles such as the Calosoma scrutator ( CARABIDAE ),

ladybirds such as Coleomegilla maculata ( COCCINELLIDAE ),

flies such as Bonnetia comta ( TACHINIDAE ),

big-eyed bugs such as Geocoris punctipes ( LYGAEIDAE ),

assassin bugs such as Arilus cristatus ( REDUVIIDAE ),