The Life-History and Anatomy of Moths 



known as " loopers " or "measuring-worms." When, as is the 

 case with many genera of the Noctuidce, a less complete abortion 

 of the prolegs occurs, and only a partial approximation to the 

 movement employed by the larvae of the Geometridce is wit- 

 nessed, the caterpillars are said to be " half-loopers," or "semi- 

 loopers." As examples of such caterpillars we may cite those 

 belonging to the genus Plusia, in which there are only two pairs 

 of abdominal prolegs. In the family of the Megalopygidce the 

 prolegs are supplemented by sucker-like pads on the somites 

 ranging from the fifth to the tenth, inclusive. In the Cochlidiidce 

 the prolegs are wanting, their function being wholly assumed by 

 such sucker-like pads, ranging on the ventral surface from the 

 fourth to the eleventh somites, inclusive. In the Eriocephalidx, 

 which are regarded as ancestral forms, there are, as has been 

 pointed out by Dr. T. A. Chapman, eight pairs of abdominal 

 prolegs and an abdominal sucker situated upon the ninth and 

 tenth somites, having the shape of a trefoil or clover leaf. These 

 larvae are further remarkable in having well-developed antennae. 



After the larvae have emerged from the egg and fed for a 

 longer or shorter period, the outer skin, or epidermis, becomes 

 too small to admit of further growth, and the insect then molts, 

 or sheds its skin, and resumes feeding until increased develop- 

 ment makes another molt necessary. The number of such 

 molts varies in the case of different species. Ordinarily, hetero- 

 cerous caterpillars do not molt more than five times before trans- 

 forming into pupae, but some genera molt as often as ten times, 

 while others only molt thrice. The skin which is cast off pre- 

 serves the outline not only of the body, but also of the horn-like 

 processes, the hairs, and various other appendages attached to 

 the body at the time of molting. The molting period is a 

 critical time in the life of larvae, and those who are endeavoring 

 to rear them should never disturb them in the least at this time. 



The bodies of the larvae of moths are covered with tubercles, 

 the location and arrangement of which has in recent years 

 received considerable attention from students, and is thought to 

 furnish a clue to the lines of descent of certain families. These 

 tubercles sometimes carry only a single hair, in other cases they 

 carry large tufts of hairs; they may be small and inconspicuous, 

 or they may be developed until they assume the form of great 



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