INSECTS 



73 



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

 holding specimens. Cigar boxes may be used for holding collec- 

 tions 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 collections. 



It is pleasant and profitable to take to the fields a small book 

 like this one, or even Comstock's " Manual of Insects," or Kel- 

 logg's " American Insects," and study the insects and their habits 

 where they are found. 



Captured insects which, in either the larval or perfect 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. Beneficial 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 (e.g. a wasp, Fig. 122) is divided 

 by means of two marked narrowings into three parts : 

 the head (A'), chest (B), and 

 abdomen {H). 



The head is a freely movable 

 capsule bearing four pairs of 

 appendages. Hence it is re- 

 garded as having been formed 

 by the union of four rings, 

 since the ancestor of the insects 

 is believed to have consisted 

 of similar rings, each ring 

 bearing a pair of unspecialized 

 legs. The early grub or caterpillar stage of insects is 

 believed to resemble somewhat the ancestral form. 



The typical mouth parts of an insect (Fig. 123), named 

 in order from above, are (1) an upper lip (labrum, ol), (2) a 



Fig. 122. — A Wasp. 



