474 M. Edmond Bordage on the 



After having announced in this island the presence of an 

 entomological species hitherto unknown, and which, perhaps, 

 has been introduced there from one of the two other Masca- 

 reignes in relatively recent times, I am pleased to be able to 

 make known certain remarkable details as to the habits of 

 the Evanice. The perfect insect lives upon plants, but the 

 larva is parasitic. According to some authors — Reid, Dr. Ar- 

 nold (cited by Kirby and Spence, Introd. to Entom. vol. i. 

 p. 580, and vol. iv. p. 216) — this larva is parasitic on the 

 Blattce. It is difficult to suppose that the egg which gives 

 birth to the parasite can be introduced into the body of the 

 Blatta when this latter has undergone all its metamorphoses ; 

 the teguments of the Orthopter would certainly be too re- 

 sistant for the ovipositor of the Evania to penetrate them. 

 It is even probable that this feeble instrument would find 

 great difficulty in forcing its way between two segments of 

 the body of the Blatta. One is therefore forced to admit that 

 the introduction of the tgg takes place when the Orthopter 

 is still in the larval or nymph state (immediately after each 

 change the body is white and soft) . Maybe that these events 

 take place in this manner with certain species of Evania ; but 

 I strongly believe that the observations of MacLeay, Lewis, 

 and Stephens (quoted by Westwood, Trans. Ent. Soc. 

 vol. iii. p. 240) are more exact, and that in a general way 

 the young Evanice live as p;irasites in the oothecas of the 

 Blatta. At least, this is the case with E. Desjardinsii. 

 This species, which measures from 7-8 millim. after its com- 

 plete development, undergoes all its metamorphoses in the 

 interior of an ootheca 12-15 millim. in length, belonging 

 sometimes to Blatta americanaj sometimes to B. maderce. 

 The larva does not weave any cocoon properly so-called ; 

 it contents itself with secreting a few threads of greyish silk 

 of rather coarse texture, applied to the wall of the ovarian 

 capsule. This silk isolates the larva from the small debris 

 arising from the destruction of the partitions of the ootheca. 



Recently I have been able to observe Evanice penetrating 

 into houses. They are probably in search of the oothecse 

 deposited by Blattce in dark corners ; but, despite all my 

 care, I have never been able to catch them in the act. I 

 have only once seen E. Desjardinsii follow a Blatta ; this 

 was in the June of this year in the botanic garden of Saint- 

 Denis. The Hyraenopter flew round and round a female 

 Blatta americana, whose ootheca, still soft and whitish, pro- 

 truded from the extremity of the abdomen. The Orthopter, 

 half-blinded by the brilliant light, fled before the aggressor, and 

 succeeded in taking refuge in a crack which presented itself 

 in the bark of a tree ; this put an end to ray observations, of 



