3° 



THE STUDY OF INSECTS 



ulated with the head in front of the eyes or between them. They vary 

 in form. In some insects they are thread-like, consisting of a series of 

 similar segments; in others certain segments are greatly modified in 

 form. 



The various forms of antennas arc designated by special terms. The 

 more common of these forms are represented in Figure 61. These are as 

 follows: 



i. Setaceous or bristle-like, in which the segments are successively 

 smaller and smaller, the whole organ tapering to a point. 



2. Filiform or thread-like, in which each segment is of nearly 



Various forms of an- 



Fig. 62. — Mouth-parts of the red- 

 legged Locust. 



uniform thickness throughout its length; and the antenna as a whole 

 tapers gradually, if at all, towards the tip. 



3. Moniliform or necklace-form, in which the segments are more or 

 less globose, suggesting a string of beads. 



4. Serrate or saw-like, in which the segments are triangular, and pro- 

 ject like the teeth of a saw. 



5. Pectinate or comb-like, in which the segments have long processes 

 on one side, like the teeth of a comb, or on both sides, like a feather. 



6. Clavatc or club-shaped, in which the segments become gradually 

 broader, so that the whole organ assumes the form of a club. 



7. Capitate or with a head, in which the terminal segment or seg- 

 ments form a large knob. 



8. Lamellate in which the segments that compose the knob are ex- 

 tended on one side into broad plates. 



The mouth-parts . — No organs in the body of an insect vary in form 

 to a greater degree than do the mouth-parts. Thus with some the 

 mouth is formed for biting, while with others it is formed for sucking. 

 Among the biting insects some are predacious, and have jaws fitted for 

 seizing and tearing their prey; others feed upon vegetable matter, and 



