298 TRANS. ST. LOUIS ACAD. SCIENCE. 



MiCROPLiTis Fr., 3 cubital cells: 2d and 3d abdominal joints 

 confluent. Ovipositor concealed. Posterior coxae not large : 

 spurs of posterior tibise less than half the length of the first 

 tarsal joint. Mesopleura with a punctured groove. Cocoons 

 leathery, without loose silk. 



MiCROGASTER Latr., 3 cubital cells: 2d and 3d abdominal joints 

 distinctly separated. Ovipositor exserted. Posterior coxae 

 unusually large : spurs of posterior tibiae more than one-half 

 the length of the first tarsal joint. Cocoons white and with 

 loose silk. 



Apanteles Fr., 2 cubital cells : 2d and 3d abdominal joints 

 separated. Ovipositor long or short. Mesopleura with no 

 distinct groove. Cocoons with loose silk, 



HABITS OF the GROUP. 



The Microgasters are, with few if any exceptions,* confined in 

 their attacks to the larvae of Lepidoptera. The Microgaster lar- 

 va that I have observed are all apodous grubs, of which that of 

 Apanteles aletice may serve as an example. 



A. aleti^. Larva. — 4 mm. in length. A smooth, membeiiess grub, 

 narrowing towards the head and thickest near the posterior end ; the head 

 nearly as large as the ist joint, the sutures between the joints rather 

 indistinct. The mouth parts (Fig. i, b) minute, similar to those of other 

 hjmenopterous parasites. The 6th, 7th, Sth and 9th joints behind the 

 head provided with a pair of prominent lateral tubercles; pairs of slighter 

 tubercles on the 5th and loth joints. Color white, or tinged with green 

 or yellow. 



They always emerge from their host before it attains the pupa 

 state to spin their cocoons. Sometimes but a single larva of the 

 Microgaster is nourished by the caterpillar, although in most 

 cases many feed in company, and, emerging at the same time, 



* Reinhard (1. c.) gives a list of the exceptions, there being' 4 cases of parasitism on 

 Beetles, 2 on Saw-flies, i on a Gall-fly, all recorded by Ratzeburg; a case of parasitism 

 on a Gall fly observed by Mayr; one on a Fly by Haliday and another by Bouche, and two 

 species bred from Cecidomyia rosaria. one by Ratzeburg and one by Mayr. But, as all these 

 species have also been bred from Lepidopterous larva;, Reinhard considers that these com. 

 paratively few observations are of questionable accuracy. Still another case of parasitism 

 upon Diptera (^M. obscurus Nees upon Trypeta arniccE) is mentioned by Giraud and La- 

 boulbene in the "Annales de la Socit=te enlomologique de France" for 1S77, p. 413; and 

 mention is there also made of the parasitism of Af. ^allicolus upon Arthrolysis Giijyoni, 

 a Chalcid, in the galls made by a moth, CEcoceris Guyone/la, on Limonastrum. But no par- 

 ticulars are given regarding the parasitism upon Trypeta ; and a reference to the original 

 description (Ann. Soc. ent. Fr., 1859, p. 476) shows that it was upon the moth larva that the 

 M. gallicohis fed. I find in my notes the record of a species reared from the larva of what 

 may have been Odontota rubra, but possibly some Lepidopterous larva was mining the 

 same leaves. 



