INSECTS 73 



the flame being led through the gasoline-saturated air to the vessel 

 containing it.) 



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 is divided by means of two marked 

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

 domen. 



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 

 of four rings, since the ancestor of 

 the insects is believed to have con- 

 sisted of similar rings, each ring 

 bearing a pair of unspecialized legs. FIG. 122. YELLOW FEVER 



/-p., i ,,. r MOSQUITO, showing head, 



The typical mouth parts of an 



thorax, abdomen. 



insect (Fig. 123) named in order 



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



