In a vegetable garden, the gardener has to contend with all innumerable kinds of pests from time to time, but chemists have made much progress over the years in finding answers to pest problems. Once a gardener has learned to recognize what damage each pest causes, he will find they are controllable if steps are taken immediately after beginning of trouble. In some cases, prevention rather than cure is the vital thing.
An instance is maggots that ruin ripe raspberries: the fly that lays eggs on the raspberry fruits does this while the flowering season is on, and preventive sprays must be used then for they are useless when the maggot is already inside the fruit.
Here a list of some more vegetable garden pests is supplied with information on damage they cause and preventive measures that should be taken.
- Identifying and Controlling Garden Pests
How to recognize and destroy Rose Leaf Hoppers, Sawflies, Scale Insects, Slugs, Snails, Symphilids, Thrips, Wasps, Weevils, Whiteflies, Wireworms and Woodlice.
Following pests are discussed in here:
- Rose Leaf Hoppers
- Scale Insects
- Slugs and Snails
Rose Leaf Hoppers
These small yellow sap sucking insects can be seen in hot, dry weather on the undersides of rose leaves. The foliage becomes mottled and turns yellow; in severe attacks the plants may be completely defoliated. Spray the leaves, particularly the undersides with BHC, DDT, derris or malathion as soon as the damage is seen, and repeat if necessary at fortnightly intervals.
The larvae or caterpillars of these small sawflies can cause serious damage to fruit, vegetables and flowers.
Adult sawflies lay their eggs in apple and plum blossoms. The creamy white, fat caterpillars begin to bore into the fruitlets in June, leaving ribbon like scars across the fruits, which have an obnoxious smell when cut. Spray with BHC at petal fall. Applications in two succeeding years should be sufficient to get rid of these pests.
The green and black speckled larvae are serious pests on gooseberry bushes. They feed rapidly on the foliage, crippling the plants to such an extent that they will not fruit the season. As soon as the larvae is seen, spray or dust with DDT, derris, malathion, and if necessary repeat at monthly intervals.
Pear and cherry sawfly
Sometimes known as slugworms, these black caterpillars attack the upper surfaces of the leaves, stunting the growth. Spray or dust with BHC at petal fall.
Rose leaf-rolling sawfly
The black, shiny larvae feed on the surface of rose leaves, which curl up, reducing growth. Pick off and burn infested leaves, or spray with DDT, derris or malathion. Sprays must be applied before the leaves curl.
Larvae of similar sawflies may infest leaves of irises, spiraea, and polygonatum (solomons seal). Spray with DDT.
Several species of these small, hard coated insects suck the sap of ornamental and fruit trees, and herbaceous and greenhouse plants, often causing them to wilt. They are practically immobile, and resemble blisters on the bark, stems and leaves. Many species excrete honeydew, leading on attack by sooty mould fungus.
Mussel scale insect
The trunks of neglected apple, pear, plum and cherry trees and the stems of cotoneasters and ceanothus, may be infested by mussel scale insects.
Soft scale insects
Generally ivy, holly, and camellias are attacked by soft scale insects. They are also serious pests of green house plants. To control all scale insects, winter wash deciduous trees with tar oil and spray ornamental trees and shrubs with whit oil and nicotine or DDT with malathion.
Slugs and Snails
These gastropods cause great damage. Field and garden slugs and snails eat the low hanging foliage and often the flower heads and upper leaves of numerous herbaceous plants and vegetables. Underground, keeled slugs feed off bulbs, roots and tubers, causing widespread injury and loss of crop. On strawberries, slugs can cause severe damage by eating large holes in the fruits. Slugs and snails are nocturnal feeders. By day, they hide under stones, leaves and rubbish in dark, cool and moist places.
Destroy them with poisoned bait. This is made by mixing 1 part of methaldehyde with 2 of bran. Place the mixture on the ground near susceptible plants, and cover with a propped up tile or piece of grass to protect it from rain. Slug pellets can be bough readymade or one of the proprietary liquid slug killers can be watered in. Lime is disliked by slugs and snails, and may be sprinkled round seedlings or valuable plants.
Minute, barely visible soils pests occurring generally under glass, and on a number of outdoor crops. They attack a wide variety of plants -- tomatoes, lettuces, cucumbers, anemones, sweet peas and primulas -- by chewing off the root hairs. With seedlings, this can result in crop failure. With infested mature plants, the lower leaves turn yellow and the top ones dark blue.
Work gamma-BHC into the soil before planting susceptible crops. Other methods, such as steam sterilization, may be used on cucumber beds.
These tiny elongated insects infest greenhouse plants, and also attack herbaceous plants outdoors. They puncture and tear minute holes in leaves, which assume a silvery appearance. At a later stage they pierce the petals producing white spots. Thrips may also transmit virus diseases, especially spotted wilt virus of tomatoes.
The thrips which attack gladioli and sometimes irises, lilies and freesias, over winter on the corms. When the young shoots break through, they show silvery streaks, and the flower petals have unsightly white spots. Dust the corms with BHC powder before planting and dust or spray the young foliage with DDT, BHC , derris, malathion or nicotine.
Cyclamens, carnations, fuchsias, roses and tomatoes are chief host plants. Control greenhouse thrips by fumigation with nicotine or DDT. Dimethoate, malathion, and BHC smokes or sprays may also be used. If necessary, repeat the applications.
If dry, hot weather pea thrips are found in large numbers on young developing pea pods. They tear at the surface and cause twisted growth and malformation, and silvery leaves. Spray or dust as soon as damage is seen with DDT, BHC, derris, malathion or nicotine and repeat after 10 days during serious infestation.
Wasps feed on most top fruits, gnawing holes in apples, pears, and plums. The spoiled fruits are liable to attack by fungal diseases, especially brown rot, which is difficult to control.
Control by destroying the wasp nests. The nests, often built in underground holes, in roofs or under the eaves, are best attacked in the evening when the wasps head for home. Place derris dust or wettable DDT powder in the nests and block the entrance holes with damp sacking or grass turves. The nests may also be destroyed by pouring carbon tetrachloride, paraffin or petrol in the entrance holes.
A large family of small, active beetles, distinguished by elongated snouts. Both the adults and the larvae damage fruits and plants in the garden.
Apple blossom weevil
In March, the adult females deposit their eggs in flower trusses of apples, pears and quinces. The cream colored grubs hatch at pink bud stage and feed inside the buds, causing the petals to close over and form a brown cap. DDT or BHC applied in early spring to kill aphides will destroy apple blossom weevil at the same time.
Clay colored weevil
Adult weevils are destructive to the foliage, flowers and fruit buds of top and soft fruit and rambler roses. They particularly attack the buds of newly grafted trees. They are nocturnal feeders, and are not easy to control. New grafts on trees can be protected by grease bands or by DDT sprayed below the graft as soon as it is made. Spray a second time if further damage is evident.
Leaf eating weevil
Considerable damage can be done in spring to fruit tree leaves and blossom by these insects. Routine sprays in early spring of DDT or BHC should prevent infestation.
Pea and bean weevil
The adults are serious pests, biting regular segments from the edges of leaves. He growing shoots of young plants are also attacked, and growth is checked. One application of BHC or malathion as soon as the damage is seen is usually sufficient.
Turnip gall weevil
The presence of this pest may be indicated by swellings on the roots of cabbage or cauliflower seedlings ready to plant out. The swellings or galls contain the weevil grubs and such plants should be destroyed.
Probably the most serious pest in the greenhouse. The adults feed at night on the foliage of great number of pot plants, and the larvae damage the roots and underground stems. Outside, the weevils damage the foliage of polyanthuses and rhododendrons and the roots of many alpine plants.
Dust with DDT in the greenhouse and outdoors, or trap the weevils rolled up corrugated paper or pieces of sacking. The insects will hide there and can then be destroyed.
The most abundant and widespread greenhouse pests. Adult whiteflies are small, white, moth like insects, found in dense clusters on the underside of leaves. Adults and nymphs feed mainly on foliage of tomatoes, though they attack other greenhouse plants as well. The leaves turn mottled and yellow, with subsequent loss of vigor. The nymphs also secrete a sticky honeydew, on which the sooty mould fungus develops, to distort the plants still further.
Fumigate with BHC or DDT, or spray with DDT, malathion or dimethoate. The pests are not easily eradicated, and a number of repeated applications may be necessary.
Outdoors, the whiteflies are significant only in brassicas, where they may attack the edible parts. Spray or dust with DDT.
Grey, hard-skinned creatures found in damp and shady parts of the garden where they feed on decaying vegetable matter. They are nocturnal feeders and cause serious damage only in humid conditions under glass; or outdoors if they are present in large numbers. They feed on stems, leaves and roots.
Clear away all garden rubbish, and eliminate dark, damp nesting places. Dust or spray hiding places and infested areas with DDT or BHC, or trap the insects in hollowed out potatoes and oranges.
The yellow threadlike larvae of the click beetle, found in the soil of most gardens. The grubs feed on the roots of underground parts of many plants, and are particularly troublesome in seedling beds. Symptoms of damage are yellowing and wilting of the foliage. Young plants may die. Fork gamma-BHC dust into the soil before planting or sowing.