198 HYMENOPTERA. 



pale honey-yellow species, with a long club-shaped abdomen. 

 It lives in Cuba. 



Rogas is a genus differing from Bracon in having the three 

 first abdominal j-ings long, forming a slender petiole. 



In Microgaster, a genus containing numerous species, the 

 antenuae are eighteen-jointed, and the abdomen is shorter than 

 usual, and clavate. There are two or three 

 subcostal cells, the second very small. 3Ii- 

 crogaster neplio})tericls (Plate 3, figs. 3, 3 a) is 

 parasitic on Nephopter^'x Edmandsii, found in 

 the cells of the Humble-bee. 



Aphidias^ the parasite of the Plant-lice, is 

 a most A'aluable ally of man. It is known by 

 its small size, and by having the second and 

 third segments of the abdomen moving free on 

 Fig. 132. each other. There are three cubital cells, though 



the wings are sometimes wanting. Aphidius (Praon) avena- 

 pMs of Fitch, the Oat-louse Aphidius, is black with honey- 

 yellow legs, and is one-tenth of an inch long. Ajjhidiv.s 

 (Toxares) triticapMs Fitch, the Wheat-louse Aphidius, is black, 

 shining, with thread-like antennae composed of twenty-five 

 joints. Its length is .08 inch. Frequently the large size of 

 the parasite causes the body of the dead Aphis to SAvell out 

 into a globular form. 



Pkoctotkypid^ (Proctotri(pn) Latreille. Egg-parasites. 

 In this family are placed very minute species of parasitic Ich- 

 neumon-like Hymenopters which have rather long and slender 

 bodies, with straight or elbowed antenna of various lengths, 

 often haired on the joints, usually teu to fifteen, sometimes only 

 eight in number, while the wings are covered with minute hairs 

 and most of the nervures arc abseut. The maxillary palpi are 

 three to six, the labial palpi usually three-jointed. The abdo- 

 men has from five to seven joints, and the tarsi are mostly five- 

 jointed, rarely four-jointed. These insects are often so minute 

 that they can scarcely be distinguished by the naked eye unless 

 it is specially trained; they are black or brown, and very 

 active in their habits. They may be swept off" grass and 

 herbage, from aquatic plants, or from hot sand-banks. They 



