The Life-History and Anatomy of Moths 



The head is usually prominent, and is provided with man- 

 dibles, or jaws, eyes, rudimentary antennae, maxillae, palpi, and 

 a spinneret for the production of silk. The head may be 

 globular, hemispherical, or conoid. It is sometimes cleft on top, 

 or bifid. It is generally more or less retractile, or capable of 

 being drawn back, so as to be partially concealed in the folds of 

 the anterior somite of the body. 



Of the thirteen somites forming the body of the caterpillar, 

 the three foremost are thoracic, and each is furnished with a pair 

 of legs which correspond to the six legs of the perfect insect, or 

 imago. The last two somites of the body are often so closely 

 united with each other as to be superficially indistinguishable. 

 The somites from the third to the eleventh inclusive are provided 

 on either side with spiracles connecting with the tracheae, through 

 which the creature receives the external air in order to the oxy- 

 dization of the waste products of the circulation. 



Fig. 4. Larva oiHyloicus kaltnia: a, thoracic legs; b, prolegs; 

 c, anal proleg; d, anal horn; e, head. 



The body is usually supported at the middle and at the end 

 by prolegs, or false legs. In the majority of families there are 

 four pairs of these prolegs, situated upon the sixth, seventh, 

 eighth, and ninth somites, and a fifth pair situated on the 

 thirteenth or last somite. The latter pair are called the anal 

 prolegs. In the larvae of the greater portion of the Geometrida, 

 and in those of numerous Noctuidce, the prolegs are reduced in 

 number, and in many of the Psychidce they appear to be wholly 

 wanting. In most of the Geometridcv the pair found on the 

 ninth and thirteenth somites are the only prolegs, and therefore 

 in order to progress the creature makes a series of movements 

 in which the body is looped upward. These caterpillars are 



