CLASSIFICATION OF INSECTS. 15 



received any general taxonomic treatment, although those of 

 certain groups had previously been given attention by Packard 

 and others, and those of many species had been described. As 

 we should expect from the quiescent condition of the pupa it 

 presents few characters other than those derived directly from 

 the more or less fully developed external structure of the con- 

 tained imago. Indeed, the cremaster, certain locomotory spines 

 on the abdomen and tubercles on the thorax, are practically the 

 only characters present which may be regarded as independent 

 pupal modifications. Consequently, they are of much less in- 

 terest than the larva?, although Miss Mosher ('16) has been able 

 to base, on the characters of the pupae workable keys for identifi- 

 cation of the families and of various groups of genera. 



The Hymenoptera are perhaps the most remarkable group of 

 insects in relation to their post-embryonic development as they 

 are also in several other respects. In this group, as already 

 stated, the larvae of only the most generalized families, the saw- 

 flies, retain the typical eruciform larva. They are in general 

 appearance very much like Lepidopterous caterpillars, although 

 differing at once in the minute structure of the .legs and in the 

 number of the abdominal ones. I am not aware that anyone 

 has attempted a general classification of the saw-flies on the 

 basis of larval structures although the larvae of a large number of 

 species have been described, and a very interesting account of 

 the external anatomy has been given by MacGillivray ('13). 

 Many are leaf-feeding in habits and show color patterns similar to 

 those of the true caterpillars. 



The larvae of all the other groups of Hymenoptera are very 

 greatly modified and hypermetamorphosis occurs in a number 

 of cases. 



Comparatively little is known of the larvae of the several 

 families of parasitic Hymenoptera, but those of some of the 

 members of this group are very remarkable. In the later stages, 

 nearly all are apodous, of very simple form, and without notice- 

 able peculiarities. In the earlier stages, however, many strangely 

 modified types are known which appear to be highly adapted to 

 their mode of life. Some of these in which marked hypermeta- 

 morphosis occurs may be illustrated by Synopeas which has been 



