28 ILLINOIS BIOLOGICAL MONOGRAPHS [260 



on each margin of the head in the Coccinellinae. This fact tends to show 

 a complete reduction of the sutures which are distinct in Epilachna and 

 are entirely wanting or only slightly indicated in the Hyperaspini. 



The condition of the armature of the body also shows a like reduction. 

 In both Epilachna and Chelymorpha scoli are present. In Chilocorus the 

 scoli are replaced by senti and in those forms which show a further reduc- 

 tion of the epicranial arms we find that there is a further reduction in the 

 armature of the body. In Hippodamia, Coccinella, Adalia, Anatis, and 

 Microweisea, forms in which the epicranial arms alone are present, the 

 armature consists of parascoli, strumae, verrucae, and chalazae or setae; 

 while in the Hyperaspini in which the epicranial suture is wanting the body 

 is provided only with setae. The condition of the scoli in Epilachna might 

 easily be taken as a highly specialized characteristic, but when one studies 

 the characteristics of the progenitors of the Coccinellidae, he finds such a 

 condition in the armature of the body as is found in the Epilachninae. 

 There is a further likeness between the Chrysomelidae and the Epilach- 

 ninae that seems also to be of importance, that is the food habits of the 

 two are almost identical, as both are phytophagous. The Epilachninae 

 are perhaps the only group of coccinellids that are entirely phytophagous 

 in both the larval and adult stages. 



The fact that the setae in Hyperaspini show an apparently generalized 

 condition, while the epicranial suture is absent in the adult larval stages 

 and present in the first larval stages, surely a specialized condition, does 

 not interfere with this proposed classification. For specialization, as 

 Comstock has pointed out, may take place in two wholly different ways. 

 "First, by the addition or complication of parts, specialization by addition; 

 second, by the reduction in the number or the complexity of the parts, 

 specialization by reduction." The latter is considered to be the case in 

 the Hyperaspini; the primitive scoli have been reduced to setae. Granting 

 this to be true, we can readily see that these two wholly different charac- 

 teristics, the condition of the scoli and the epicranial suture, show in a 

 very striking way the presence of specialization in Hyperaspini and of 

 generalization in the Epilachninae. In the first case there is the absence 

 of the epicranial stem, only an indication of the clypeal suture, and a 

 reduction of the scoli to setae; while in the latter there is the presence of 

 the epicranial and clypeal sutures and of scoli similar in form to those of 

 Chelymorpha. 



Since, as Comstock has shown, there is such a thing as specialization 

 by reduction and since the progenitors of the coccinellids, as nearly as we 

 can ascertain, have an epicranial and a clypeal suture and a well-developed 

 system of scoli, it seems to me altogether logical, and with the evidence 

 at hand quite clear that the Epilachninae represent a generalized type of 

 coccinellid larvae, though at a first glance they may appear to be highly 

 specialized. 



