DO not be taken in by the miniscule size of the creatures called insects. the problems created by them are enormous. A gardener’s nightmare, they not only devour the fruits of hard labour but at times cause permanent damage to plants. In case of short duration annuals, they may cause complete loss of foliage.
Insects have been an obstinate companion of mankind through ages. It is so due to many reasons. The structural and bodily changes even within a single life cycle — from eggs, larvae, pupa to the adult stage —has enabled them to tide over the changing weathers. Even their food requirements and habitats have striking variation within one generation, making it possible for them to depend upon different kinds of host plants and leaving no scope for competition among themselves.
The damage caused by
insects is of various types. Depending upon the kind of mouth parts,
some suck sap from leaves causing curling and cupping, both upwards
and downwards. This is noticeable in the case of brinjals, citrus
plants, peach, plum, etc, and is mainly caused by aphids, jassids and
thrips. Then there are those that have cutting type of mouth parts
like in the case of larvae. Some larvae like those of a
lemon-butterfly are so efficient cutters that even a single larvae can
make a full leaf vanish within five minutes. Using their sharp and
strong mendibles, some of the larvae, like those of Inderbela species,
bore a hole in the trunk of a tree to make it their abode, thus
disrupting the food conduction channels. They also attack the tree
bark and damage it.
Remember, a few years ago, there was a rumour that a snake had died under the wheel of a truck and its image had appeared on the kaddu-tori leaves. People stopped eating such vegetables. In fact, it was nothing but leaf miner that had appeared on leaves. The insect is so called as it makes mines on the leaf surface. Insects like scales, mango meally bug, etc, also have a protective covering of a waxy substance over their body. They are not so easy to control. In fact, apart from destroying various plant parts, insects like aphids, white fly, citrus psylla, etc, are the carriers of various deadly viruses. It is, therefore, important to control them as soon as they make an appearance.
Broadly speaking, insecticides like
rogor or metasystox are very effective against insects like leaf miner,
aphids and even scales. Such insecticides are systemic and go into the
system of the plant. The insects die when they suck at the poisoned sap.
One millilitre of the insecticide dissolved in one litre of water does
the needful. To measure the chemical, use the small cap of the bottle,
which roughly accommodates five millilitre. Similarly insecticides like
sevin and thiodam are quite effective against caterpillars.
Two-and-a-half gram of sevin, a powder, or one-and-a-half millilitre of
thiodam liquid when used with one litre of water are quite effective.