103 



Fig. 15.— Centistes Americana. 

 (original). 



Imago, enlarged 



AwaitiDg the fortbcoming consideration of this genus in Mr. MarshalPs 

 Monograph of the British Braconidse, however, we shall not attempt its 

 characterization at present, but would simply propose for it the provis- 

 ional name of Centistes americana. 



The so called Microctonus terminatns reared by Audouin, Eatzeburg, 

 and Scheffer from Coccinella si)p. proves, likewise, to be no Microcto- 

 nus but to belong to the well-known genus Ferilitus. (See Kirchner's 

 Catalogus Hymenopterorum Europse, and Marshall's Monogr. Brit., 

 Bracon., Trans. Lond. Ent. Soc. 1887, Part II, p. 53.) 



The i^arasitic habits of Microc- 

 tonus proper are not known. All 

 of the subfamily of the Bracon- 

 id?e Polymorph! to which it be- 

 longs, viz, the Euphorinse, are 

 however. Coleopterous parasites 

 in Europe so far as known. 



Eatzeburg's interesting ac- 

 count of the habits of P. termi- 

 natns (Nees) indicates that it 

 works in a manner almost pre- 

 cisely similar to our American 

 parasite and we therefore print a translation of his account : 



In 1850 I bred three females, all being found in very strange situations in the vicinity 

 of Neustadt : Living specimens of Coccinella 5-punctata. and C. 7-punctata were sit- 

 ting or hanging (once in a rolled-up leaf) on shrubs and carried under the abdomen 

 a gray, pear-shaped, subtransparent cocoon surrounded with loose silken threads. 

 From the fact that the Coccinella clasped the cocoon with the legs and got thus en- 

 tangled in the silk, the cocoon was closely applied to the abdomen, and I had some 

 trouble in detaching the cocoon when the Ichneumons (from June 10-14) had hatched 

 after cutting open the cocoon. Two CoccinelljB were still alive as long as the cocoon 

 was still unopened, since they moved their legs a little, but died after the Ichneumon 

 flies had issued. The third specimen, however, remained living for along time after- 

 wards and even could place its legs into the proper position and remain standing. I 

 have not been able to perceive the wound through which the Ichneumon larva issues 

 from the beetle. However, the Microctonus larva surely feeds within the Coccinella 

 (as already stated by Westwood) and it is probably through one of the ligaments, 

 which later closes up again, that the larva pierces through the beetle. I come to 

 this conclusion ; first, I found upon dissection of a recently dead Coccinella that all in- 

 testines were shriveled up and pressed onto the walls ; secondly, I have observed the 

 sting by which the Ichneumon Fly deposits the egg. 



To a lively female Microctonus, which I had kept alone for two days in a glass box, 

 I placed a Coccinella 7-punctata. At once the attention of the Microctonus was 

 aroused ; she ran to the place where the Coccinella was and closely examined it from 

 all sides, running forward and backward in a very comical way. Immediately after- 

 wards she prepared to sting in the same way as described by me in Aphidius aphidi- 

 vorus (I, p. 50). The abdomen, pear-shaped in repose, became long and thin ; the 

 ovipositor protruded more, only on the tip surrounded and conducted by the sheats. 

 The sting was repeated about six to ten times in one minute and always directed 

 against the incisures of the body (usually of the abdomen). Within one hour the 

 female thus attacked three or four times the beetle, which only occasionally moved. 

 Since the Ichneumon $ was not impregnated I could not expect to get any progeny. 



