VOI 

 18'Jl 



y.j\'/] PROCKEDINGft) OF TUK NATIONAL MUSEUM. 575 



gr(i(fii and HaUicheUa tarsalis, while there is al.so a record to th«' eU'eet 

 that Chalets minuta has been reared from insects of this jf«'nus. These 

 parasites presumably issue from the cocoons of the ant lions, I have 

 alreadj- summarized theparasitesof the llemerohUmv in the Proccedinj^s 

 of the Enromological Society of Washinjittou, Vol. ii, pp. VS.\ and lL'4. 

 No chalcidids are known to infest these insects in Europe, but in this 

 country the eucyrtine genus Isodromus is reared from the cocoons of 

 Chrysopa. The Chrysopa larva is evidently pierced by IfindroviKs when 

 full grown, for it invariably succeeds in si)inning its cocoon. A species 

 of rerihunpus has also been sent in from Los Angeles, Cal., by ]\Ii. 1). 

 W. Coquillet, who reared it from a Cryso])a cocoon. Mr. N. lianks has 

 recently sent in specimens of a Tetrastich us, which he reared from 

 these cocoons at Shrevejjort, La., the past June. This i)arasite, how- 

 ever, is undoubtedly secondary. 



HOW THE CHALCIDID LARVA LIVES. 



Tliis is a subject which greatly needs careful investigation. It is prob- 

 able that the same general facts will be observed with fhalci<lid larvae as 

 with the larva' of other parasitic hymenoptera, but even here our intbrnni- 

 tion is so slight and so contradictory that it is very diilicult to make 

 general statements. Situated at dilferent points l>etween the tissues 

 of their hosts, the quick-growing internal-feetling larva* absorb through 

 thr mouth the blood of their victims and rapidly become adnlr. The 

 old idea that they feed upon the fatty tissue in a mandibulatory man- 

 ner seems, at least in the majority of cases, to be untrue. The larva of 

 Ichneumon atropos, however, according to Newport, seems to destroy 

 part of the " fatty sacculi" of its host. The mandibles are piercing, 

 and not comminuting, and the other mouth parts are fitted for the re- 

 ception of liquid food. Exuviation has not been observed in the inter- 

 nal feeders, although Newport has seen it repeatedly with Paniscus, an 

 external parasite of lei)idoi)terous larva* ; " but," he writes, " the thrown- 

 olf covering is of such extreme tenuity and is so gradually and inq)er- 

 ceptibly removed, without interfering with the form or enlargement of 

 the body, that, hitherto, the deciduation of the tegument of the apodal 

 larva' of Ilymenoptera has always escape<l the observation of natural- 

 ists." With the internal feeders there is the same reason against sud- 

 den exuviation that there would be against the passing of excrement ; 

 either would produce inllammation and the premature death of the host. 

 And so there is no provision in the structure of these larva- tor the i)ass- 

 ing of the waste ])roducts of the body until they have reached lull 

 growth and a certain aiiumnt of vitalitv in the host insect is no longer 

 necessary to their existence. Tp to tiiis time tiie alimentary canal of 

 the parasitic larva has consisted of a simple sac, closed at its posterior 

 extremity, and with an impertbratt' intestine proceeding from it, without 

 aiL anal opening. When full growth is attained, however, and the 

 assimilation of food begins to be arrested, as no longer needed by the 



