INSECTS 73 



A cigar box and a bottle with a notched cork may be 

 used for holding specimens. Cigar boxes may be used i« >r 

 holding collections of dried insects. Cork or ribbed 

 packing paper may be fixed in the bottom for supporting 

 the insect pins. Moth balls or tobacco may be placed 

 in each box to keep out the insect pests which infest col- 

 lections. 



Captured insects which, in either the larval or the per- 

 fect stage, are injurious to vegetation, should always be 

 killed after studying their actions and external features, 

 even if the internal structure is not to be studied. Bene- 

 ficial insects, such as ladybugs, ichneumon flies, bees, 

 mantis (devil's horse), dragon flies, etc., should be set 

 free uninjured. 



Anatomy and General Characteristics of the Class 



Insecta 



The body of an insect is divided by means of two marked 

 narrowings into three parts: the head, the chest, and the 

 abdomen. 



The head is a freely movable cap- 

 sule bearing four pairs of append- 

 ages. Hence it is regarded as 

 having been formed by the union d^^af 'V^~> 



of four rings, since the ancestor of 

 tht insects is believed to have "con- 

 sisted of similar rings, each ring 

 bearing a pair of unspecialized legs. fig. 122. — yellow fever 



The typical mouth parts of an ™%Zg£* ** 

 insect (Fig. 123) named in order 

 from above, are (1) an upper lip (labrum, ol\ (2) a pair 



