128 PIMPLINE ICHNEUMONIDAE 



abdominal segments being acute instead of truncate, would seem 

 to place it in Megarhyssa. It would also seem that this might 

 be the female of M. nitida on account of the similarity of color- 

 markings, size, and its petiolated areolet. If this should prove 

 true the name M. nitida would fall into synonj-my. 



Megarhyssa atrata (Fabricius) 



Ichneumon nirula Fabricius, Spec. Insect., i, 1781, p. 436. 



The following references are in addition to those given by Dalla Torre: 



Lintner, Country Gentleman, July, 1883, p. 561. 



Harrington, Can. Ent., xix, 1887, p. 206. 



Riley, Insect Life, i, 1888-89, p. 168 et seq. 



Smith, Insects of New Jersey, 1909, p. 627. 



This species varies from about an inch to an inch and three-quarters in 

 length, with a very long, dark-browni ovipositor, which in some cases attains a 

 length of five or six inches. The head and antennae are yeUow. The ocelli 

 are embedded in a transverse dark band extending between the compound 

 eyes. There is another transverse dark band at the point of insertion of the an- 

 tennae, not quite reaching the compound eyes, and a black spot on the face just 

 above the clypeus. The ground color of the thorax is a glossy black with a 

 yellow spot in the prothorax just in front of the fore wing, one beneath the fore 

 wing, and one on each side of the propodeum near where it articulates with the 

 second abdominal segment. On each side of the mesoscutellum is a short, longi- 

 tudinal dash, while in the center of the metascutellum (generally called post- 

 scutellum) is a transverse yellow dash. The legs are yellow with the coxae, 

 middle and hind trochanters, black and the fore-trochanters partly yellow. 

 The procoxae each bear a more or less indistinguishable yellow spot. The 

 middle and posterior femora are black with yellow tips. The tibiae are yellow, 

 but the tarsal segments are darker at their outer extremities and the tips of 

 the tarsal claws are black. The wings are fusco-hyaline and show an irides- 

 cence in some lights. The stigma is pale ferruginous at its base becoming 

 darker toward its apex. The abdomen is brownish-black, some parts being 

 slightly hghter than others. 



M. atrata may be distinguished from M. lunator, greenei, 

 and mexicana by its very dark abdomen. Its yellow antennae 

 will distinguish it from nitida, canadensis, and humida. Its 

 larger size would also serve to distinguish it as well as the length 

 of the ovipositor, which is several times the length of the body. 



Its life history is similar to that of M. lunator and M. greenei 

 with which it is commonly found associated. The dates of cap- 

 ture of specimens seen range from June 2 to September 15. 



The male of M. atrata differs from the female very markedly 

 in its color markings. The structural sex differences are the 

 same in M. atrata as in M. lunator. In general the male has 



