270 SCHULTZB. 



the reason that the skin in this place is not as hard as on the thoracic seg- 

 ments, which are iDrotected by chitinous plates. The larvae of A. miliaris 

 Fabr., which live closely together in groups, act in a slightly different way. 

 If one is disturbed, it begins to flick with its old skins. The larvae sitting 

 next to it, or even the whole group, take up the motion and in unison 

 they strive to frighten the enemy away. I have noticed this action 

 repeatedly. The larva of M. trivittata Pabr., when resting, carries its 

 old skins behind, lying flat on the leaf, but when it is moving around, 

 they are pei-pendicular to the body. It also uses its old skins in a way 

 similar to A. miliaris Fabr. I have applied the following test many 

 times. The larva, when molested with a hair, tries to touch the latter 

 with the 6ld skins, with the intention evidently of removiug the annoy- 

 ing object. The pupae of Prioptera and Aspidomorplia miliaris Fabr. 

 do not retain the old sldns, but only the last one of the larval stage by 

 which they are fastened to the leaf. The newly transformed pupae are 

 extremely sensitive and when touched give several sharp fliicks. During 

 the later period of the pupal stage, they do not react as easily, the 

 reason probably being that during the early portion of this period the 

 skin is quite soft, but during the latter part hard enough to give suificient 

 protection against parasites even without the old skins or shields which 

 are retained in the other species. 



The infection by parasites probably takes place during the periods of 

 the different molts, as in those stages the larvae are quite helpless. The 

 larvae of M. trivittata Fabr. were often infested by a fly {Muscidae Tra- 

 chinae), the larva of which, affer becoming full grown, builds its pu- 

 parium inside of the larval skin of M. trivittata Fabr. Pupae of A. 

 miliaris Fabr. were often infested by a small Clialcididae,^" as many as 

 150 emerging from one pupae. 



In consideration of facts concerning the usefulness of all excremental 

 coverings, or armatures, etc., observed on the different species mentioned 

 in this paper, the theory of Candeze seems to me credible, and I believe 

 that the curious structures are used principally as a protection against 

 parasitic enemies. 



Note. — ^After my paper was in type I happened to see the following paper: 

 "On the egg-cases and early stages of some South China Cassididse" by J. C. 

 Kershaw and Frederick Muir in Trans. Ent. Soc. Land. (1907) p. 249. It is 

 worth mentioning that 0. picifrons Weise and L. philippinensis Blanch, differ also 

 in their egg-laying habits from C. obiusata Bohem. and L. chinensis Fabr., as the 

 latter species lay more than one egg under the egg cover. With- reference to 

 the summarizing sentence of Kershaw and Muir, I still believe that protection 

 against parasitic enemies is the "raison d'etre" for the development of the egg- 

 cases and larval appendages. 



" Mr. Banks and myself observed the act of copulation on these Hymenoptera. 

 The adult parasites make a few tiny holes in the pupal skin of the host. The 

 males, after emerging, stand guard around each of the holes thus made, and as 

 soon as a female comes out, the act of copulation, which is extremely short, takes 

 place. 



