44 



INSECTS ATTACKING APPLE, PEAR, PLUM, AND 

 CHERRY TREES. 



By G. Fox WILSON. 



IT is essential, in dealing with and destroying pests of any kind, to 

 have a thorough knowledge of their life histories, so as to know the 

 exact time to apply the preventive, as there is often only one period 

 in the life of an insect when it is vulnerable. 



Let us now see what the word " insect " implies. It literally 

 means any animal which has the body so divided as to seem cut into 

 successive parts, usually resembling rings of hard substance connected 

 by soft skin. 



In old entomological books it will be seen that "insects" was the 

 name given to all animals with bodies resembling a row of joints ; 

 even worms and slugs were at that time included. 



Now the name is confined to a considerably smaller group of 

 animals, the true insects, or the class Insecta of the type Arthrcpcda. 



In this diminished sense, insects are now classed as animals that 

 have a jointed body made up of a number of rings of horny substance 

 called chitine, connected by skin, so united as to form three great 

 divisions in the body, viz. the head, the thorax, and the abdomen. '< 



The head of an insect consists of four segments, which are so fused 

 together as to be undistinguishable in the adult form. 



The head always bears one pair of organs, called antennae, near 

 the eyes. Their function is not clearly understood, but they act, 

 possibly, as organs of hearing, smelling, or feeling, or perhaps of another 

 sense, of which the human being does not know. 



The length of them varies greatly, as does also the number of joints 

 in them, and insects can often be readily recognized by the shape or 

 number of joints in the antennae. 



The eyes of insects are of two kinds, simple and compound. The 

 former consists of a single eye, and is situated, in the mature insect, 

 on the upper part of the head. There may be from one to three of 

 them, the latter number being the most met with. 



The compound eyes are made up of the union of a large number of 

 hexagonal simple eyes, as many as thirty thousand. They are often 

 so large as to occupy the greater part of the head. 



The mouth parts consist of the upper lip or labrum, two pairs of 

 jaws or mandibles, maxillae, and the under lip or labium. 



The labrum is narrow and of a chitinous nature, closing the mouth 

 from above. 



The mandibles or upper jaws are fixed on either side of the opening 

 of the mouth and move horizontally. 



