Preventing Greenfly Attacks on Vegetables and Shielding Cash Crops: Simple Ways to Control and Protect.

Greenflies are soft-bodied, pear-shaped insects measuring 1mm to 5mm. Most of them are green through some may be brown, yellow, pink or black. They can be found all over the world and live on various sorts of plants. When the insect feeds on plants, the stylets (the food channel and salivary tube) pierce into the plant and may sometimes even reach the vascular tissue. The insert then sucks out the sap which passes through the sucking tube. The labium does not enter into the plant tissues but remains at the surface. Some saliva is sent out through the salivary tube. This is believed to prevent the plant juices from Coagulating.

Greenflies and their nymphs live and feed on almost all vegetable plants including those of the following families - Cabbage, Cucumber, Melon, Bean, Pea, Potato, Tomato, Lettuce and other garden crops. They also feed on ornamental plants, fruits plants such as apple and plum, cereals and important crop plants. They always choose the tender parts of these plants, such as the buds and young leaves, to feed on. They manage to hold on to slippery plant surfaces with the help of the claws on their legs.

Greenflies are very dangerous insect pests because they feed on plants as well as spread organisms which cause diseases such as blights, cankers and leaf mosaics into the plant cell. The signs which indicate that plants have been attacked by greenflies are the blighting of buds, dimpling of fruits, and curling and spotting of leaves. When large numbers of greenflies attack a plant, the plant gradually wilts and dies. They render vegetables unattractive and unmarketable, and also affect their flavour. Much expense and labour is involved in getting rid of them.

Another way in which greenflies can damage plants is by egesting a sticky, sugary substance called honeydew. This substance soon hardens and serves as a good medium for dangerous fungi to grow in. Eventually, these fungi attack the plant and spread to other plants. The honeydew also attracts certain species of ants which feed on it. Hence, large numbers of ants can often be seen on host plants for their honeydew. One of the best method is to prevent them from breeding.