Battling Insect Pests With Insecticides

Press, Volume CII, Issue 30145, 31 May 1963, Page 6

Battling Insect Pests With Insecticides

Insect pests can generally be controlled by chemicals known as insecticides. These are used only for the control of insects and will not cure or prevent diseases. Many insecticides are poisonous to some degree and all kinds should be treated With the utmost oare. Use rubber gloves when handling, wash the hands after use and wash and thoroughly clean all receptacles which may have come into contact with the chemicals. Keep them out of reach of children and do not leave empty containers lying around.

Insect pests damage plants in two different ways, depending on how they feed. Some cause damage by sucking the sap such as aphis, whilst others bite or chew pieces of the plant, as do caterpillars. Each group of insects is controlled by a different type of insecticide.

Sucking insects are controlled by a contact poison,, this is one that has to come into contact with the pest and kills it. The biting pests are controlled by a stomach poison which is sprayed onto the plant where it can be eaten by the insect. There is a new group of insecticides still very much in the experimental stage. Some are available for pest control but most are so highly poisonous that they are not available to the home gardener. These are known as systemic insecticides; the poison is taken into the sap of the plant and will kill any pest which feeds on it either by sucking or biting.

The following are a few of the commoner chemicals which can be used in the home garden and should give control of most of the pests that the home gardener is likely to encounter. These insecticides are listed under their active principals as many have a large number of trade names.

D.D.T. gives a good control t>i chewing or biting insects such as caterpillars, weevils, and grass grubs. It is fairly resistant, especially in the soil, and should not be applied to edible crops near harvesting. It is available in powder form for use as a dust, in wettable powder form for use as a spray, as an emulsion, aerosol, or as smoke bombs.

Lindane controls biting insects as well as some sucking insects Among the pests controlled are caterpillars, leaf miners, and aphis, especially woolly aphis. Its residual effect is less than D.D.T. but it should not be applied to an edible crop less than three weeks before harvesting. It is available in a similar range of forms to D.D.T. Malathion is the safest of the phosphorous insecticides jnd the only one that is available to the home gardener It is available as an emulsion or a wettable powder and its lasting properties are not very long. It is advisable not to apply vithin a week of harvesting of edible crops. It can be used to control such pests as aphis, woolly aphis, thrips. leaf hoppers, scales, and -gives some control of red spider mite. Acaricides is a group name for a number of insecticides, most of which have very long chemical names. This group of insecticides controls mites, especially red spider mite, and is available as smoke bombs, powders or liquids.

Oils are available in three iifferent grades: Winter or red oil is used only on deciduous trees and then only when the leaves have fallen and the tree is fully dormant It is largely used on fruit trees during the winter to give control of the eggs of aphis and red spider.

Intermediate oil can be safely used up to the green tip stage and will control the same pests that are controlled by red oil.

White or summer oil can be used on plants at any time of the year—when they are carrying foliage and at all times with evergreens. It gives control of scale insects and red spider mites. Metaldehyde Is used to give control of slugs and snails. These are not insects, belonging to the same family as shellfish but in the garden

they are considered along with insect pests. The metaldehyde is often mixed with bran as a bait to attract slugs and snails which appear during the night. When applying any insecticide. always follow carefully the maker’s instructions as the percentage of active ingredients varies with different proprietary preparations. Doses stronger than recommended may not give better control and could often cause damage to the plant being sprayed.