Chapter 14. 



INJURIOUS INSECTS. 



General observations on Insects and their feeding habits. 

 Insecticides and their use. Earwigs. Destructive Caterpillars 

 of Cabbage Butterflies, and the Currant, Winter, and Codling 

 Moths. The Gooseberry Saw-fly. The Pea Thrips. Wireworms. 



The next class to be considered is that of the INSECTS 

 (9), (10),* and, viewed from our present standpoint, they 

 are of greater importance than the whole of the rest of 

 the Animal Kingdom. Insects can be readily recognised 

 by the presence of a pair of antennae or feelers, six pairs 

 of legs, and the division of the body into head, thorax 

 and abdomen. Either one or two pairs of wings are almost 

 always present in adult Insects. The most remarkable 

 feature in their life-history is the fact that they pass 

 through a series of changes which we term metamorphosis. 

 On hatching from the egg, the first stage is the larva, 

 which is succeeded by that of the pupa, and from the 

 latter emerges the perfect Insect. In many Insects, how- 

 ever, the pupa is absent, and then there is a gradual growth 

 from the larva to the perfect Insect. Larvae are variously 

 known as caterpillars, maggots, or grubs, and, being 

 exclusively concerned with feeding, they are as a general 

 rule more destructive than the perfect Insects. The pupa 

 or chrysalis is purely a resting stage, no food is taken, 

 and during this period the organs and tissues of the future 

 Insect are gradually built up. It is of great importance 



* The numbers in brackets refer to the literature given at the end 

 of the final lecture. 



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