Abstract

Insects, as a group, are more injurious than beneficial to mankind. Imms (1947), has recorded seven lakhs of species of insects of which about ten thousand are known to be injurious, affecting plants and of these about five hundred are major pests. In South India alone, Ramakrishna Iyer (1932) has recorded under various families, two hundred forms causing considerable damage to the cultivated crops in some form or other. Unlike many other groups, the members of this order, with few rare exceptions, are herbivorous vertable pests during the larval stage. The larval stage is familiarly known as caterpillars. The large majority are external feeders but a good number, work unseen inside plant tissue. In a large number of cases, the plant may be disfigured, the foliage reduced considerably or the growth of the plant ratarded. Some- times the evidence of damage is seen in the form of castings on the leaves, bore-holes, scrapings, cut-ends of the leaf, fluffy secretions on the stem and dead hearts.

Keywords: