REPORT OF THE ENTOMOLOGIST. 533 



ovipositor are dark, especially at base, and the ovipositor itself is honey-yellow; the 

 legs are all honey-yellow except the tips of the huid tibiai, which are dark, 



^ . — Resembles the female, with the usual stnicitural differences. Varies consid- 

 erably in color, some specimens being almost immaculate, while others are marked 

 like tlie female. Wing venation in both sexes varies in no way from that of com- 

 viunis, and but slightly from that in other species of the genus; in that the second 

 submarginal cell is subquadrate, broadening slightly posteriorly, and in the first trans- 

 verse cul)ital nervure being confluent with the recurrent nervure. 



Described from 18 9 , 2^ specimens, all bred in District of Columbia from cocoons 

 collected near remains of larvte of Hyphantria cunea. 



The Microgaster Parasite of the Web-worm. — This insect 

 was about as numerous as the Meteo7-us, and did equally good serv- 

 ice in preventing a further increase of the cateri^illars. It appeared 

 somewhat earlier in the season, and had killed only half-grown cater- 

 pillars. From the numerous old and empty cocoons in early summer 

 it was plainly seen that a first brood had been quite numerous, and 

 that from these cocoons mainly Apanteles had been bred, and not, as 

 during the autumn, mostly secondary parasites. The white silky 

 cocoon is formed almost under the middle of a half -grown caterpil- 

 lar, and is fastened securely to the object its host happened to rest 

 upon, and but slightly to the host itself, which is readily carried to 

 the ground by wind and rain, and can therefore only be in position 

 in the more sheltered places, such as cracks and fissures of the bark 

 of trees. But one Apanteles is found in a caterpillar, so that each 

 white cocoon indicates, like a tombstone, the death of a victim. In 

 some places, and notably upon the trunks of poplars, these cocoons 

 were so numerous as to attract attention; it seemed as if the trunk 

 had been sprinkled with whitewash. But notwithstanding such vast 

 numbers, but two sj^ecimens of the architects of these neat cocoons 

 weve raised; all the rest had been parasitized by secondary parasites. 

 It is barely possible, however, that some specimens may hibernate in 

 their cocoons, since numbers of them have as yet (December 20, 188G) 

 not revealed any insects. The winged Apanteles leaves the cocoon 

 by a perfectly round orifice in the front, by cutting off a little lid, 

 which falls to the ground. Its parasites, however, leave by small 

 holes cut through the sides. These secondary parasites were very 

 common late in September and early in October, and busily engaged 

 in inserting their ovipositors through the tough cocoon into their 

 victim within. It seems as if the cocoons formed early in the season 

 were on an average a little smaller than those formed later. 



The cocoons of this Apanteles are of a uniform white color, but ex- 

 ceptionally a distinctly yellowish cocoon is found. From these yel- 

 low cocoons nothing has so far been bred, but since, as we have else- 

 where shown,* the color of the cocoon may vary in the same species, 

 it is probable that the variation here referred to is not specific. 



Not quite one-half of 1 per cent of these cocoons produced the in- 

 sect belonging to it; 99 per cent produced secondary parasites, 



Apanteles hyphantria, n. sp.— 9 . Length, 3™"". Close to Apanteles xylina, 

 Say, with which it may be compared. Differs as follows: Mesonotum without the 

 faint inedian carina or pohshed posterior margin; scutellum not pohshed; first 

 abdominal segment about as broad as long, %vith a quite distinct median carina, the 

 apex of which is pohshed, and its posterior margin broadly bilobed. In A. xylina 

 the first abdominal segment is rather slender, and longer than wide, without dis- 

 tinct carina and Avith the apex almost straight. A quite distinct carina on tlie sec- 

 ond segment, wanting in xylina. Third abdominal segment coarsely pitted at base, 



* Notes on North American IMicrogasters, &c., Trans. Saint Louis Acad. Sciences, 

 vol. 4, author's separate copy, p. 7. 



