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. 
e 
Fig. 4.— Larva of Hyloicuskalmuz: 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 Geometridce , 
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 Geometridce 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 
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