Aphids on the green tomato plant; Greenhouse whitefly – Trialeurodes vaporariorum
Insects are undoubtedly one of the most important entities in the garden, but can also be the most destructive and a bane to most home gardeners. Different kinds of insects cause various types of damage and are garden pests, and it is good to know which ones do what to take appropriate control measures.
Garden insects fall roughly into three categories: sucking insects, chewing insects, and stinging insects.
Sucking insects include all types of aphid, mealy bug, thrip, whitefly, scale, mite, and bug. Most sucking insects are minuscule, many of which are invisible to the naked eye. These insects suck the sap from young shoots and buds, causing wilting, as well as the curling and distortion of leaves and flower buds. Unfortunately, the presence of sucking insects is usually only noticed once the damage is quite severe. Sucking insects physically destroy the plants and significantly lessens their vitality. They can also transmit certain viruses.
There are some pesticides on the market to control sucking insects, including broad-spectrum pesticides, such as mercaptothion and diazinon, which can be used for chewing insects as well as sucking insects. Other pesticides, such as difocol, pirimicarb and mineral oil, are specifically used for aphids, mites, or scale.
These insects are usually large and very destructive. They chew holes in leaves and flower buds and some, such as hawkmoths and caterpillars (above), will devour the whole plant. Many chewing insects are the larvae of moths and butterflies. They include all types of caterpillar, beetle, and grasshopper. Chewing insects should be controlled as soon as they are seen, as once they have developed to their full size, they are tough to eradicate by chemical means and frequently the only way to control them, in the end, is by hand-picking them.
Pesticides specially formulated for large chewing insects, as well as for large bugs, include carbaryl, chlorpyrifos, and endosulfan.
The two most important kinds of stinging insect found in the home garden are fruit fly (above) and pumpkin fly. These two insects lay their eggs under the skin of the fruit, and the resulting maggots infest the ripening fruit, totally ruining the crop. Select pesticides, such as fenthion and tricorphon, are used to control these flies, as well as coddling moths. If regularly used from the time the fruit forms, they will ensure a clean crop.
To control insect pests, you must know what type of insect is causing the damage so that you can use the correct type of pesticide spray. A spray formulated for mites will be ineffective against large chewing insects while a broad-spectrum pesticide will be unnecessary in dealing with a few aphids. If you are unsure of what pesticide to use, consult an expert at your local garden center.