The Life-History and Anatomy of Moths 
known as “loopers” or “measuring-worms.” When, as is the 
case with many genera of the A J octuidce, 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 Eriocephalidce, 
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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