THE CHALCIDOID GENUS PERILAMPUS. 61 



not grow at all until they emerge and begin feeding outside. This 

 resemblance is not altogether lost in the later stages. Even the 

 large dorsal tubercles or projections of Orasema and Perilampus are 

 reproduced in the third-stage larva of Bhipiphorus. There is a slight 

 difference in the method of pupation, the Rhipiphorus larva leaving 

 the host to pupate wliile Orasema, when not interfered with by the 

 worker ants, and Perilampus, transform in situ. 



We have then in PerilaTnpus and Orasema an instance of hyper- 

 metamorpMsm as defined by Packard, belonging to the same type as 

 that occurring in tlie Rhipiphoridse. The planidium exists as such 

 because of the wandering and perilous life it is obliged to lead in its 

 search for a host, but soon after that host is found, the protection of 

 the cliitinous plates or the use of the ambulatorial spines no longer 

 being necessary, these accessory structures are discarded. As the 

 parasite now has easy access to an abundance of rich nutritious food 

 without the necessity of putting fortli the slightest effort it becomes 

 a mere grub — a perfect adaptation to the new mode of life. 



HOST RELATIONS OF THE GENUS PERILAMPUS. 



REARING RECORDS OF PERILAMPUS HYALINUS AT THE LABORATORY. 



We have found the native species Perilampus liyalinus to attack the 

 primary parasites of two species of Arctiidse, HypJiantria textor Harris 

 and Euchsetias egle Drury; a single notodontid, 3Ielalopha inclusa 

 Hiibner; and a saturniid, Samia cecropia L. 



The species liyalinus has shown an adaptability in the matter of 

 food habits wliich is quite unusual in an insect with such a compUcated 

 life history. We have absolute records of this species from 10 dif- 

 ferent primary parasites belonging to 2 cUfferent orders and 6 or 7 

 different genera. A diversity of liost relations as exliibited by liyalinus 

 would not be considered at all remarkable in species of a great 

 many chahddoid genera, but when we consider the circumscribed 

 method by wliich access to the host is gained, it seems, on fost 

 thought, to show a quite unusual versatihty. Wlien we come to 

 analyze the habits of the parasite more closely, however, it is at once 

 seen that the versatility is only apparent. The diversity of host rela- 

 tions is due more to a lack of discrimination than to any especial 

 adaptabihty. Precisely the same efforts are put forth by the pla- 

 nidium on the occasion of its attack upon any and all of its hosts. 

 The conditions under which it develops are somewhat variable, but 

 even here the actual stimulus which causes the change from endo- 

 parasitism to ectoparasitism is the same, namely, that of liistolysis 

 in the host larva. 



