3IO TRANS. ST. LOUIS ACAD. SCIENCE. 



coxtE red, and the basal half of the anteurice yellow. This variety- 

 may be named rufocoxalis. That it is only a variety is evident 

 from my having bred in May from similar bunches of cocoons, 

 both in Missouri and in Washington, specimens which agree in 

 all characters, but vary in having the third joint of the abdomen 

 either black, piceous, or red, and in the first and second joints- 

 also being more or less red, and in the coxae being blackish at 

 the base. Army-worm specimens bred in Connecticut in 1880 

 from irregular masses of whitish cocoons not concealed by a 

 covering of loose silk difler from the typical congregatus in hav- 

 ing lateral red fascige on the third and fourth, and in the male 

 on the fifth, joints of the abdomen, the fasciae in the male being 

 sometimes continuous. One specimen has a pair of red dots on 

 the third joint only. But in other respects these parasites of the 

 Army-worm agree with those from the Sphinges.* A variety 

 which I have bred from Anna virginka in Missouri, and which 

 may be named scitulus^ varies further in having the base of the 

 third abdominal joint more or less sculptured and in the abdomen 

 beyond this, except along the middle, and in the entire under sur- 

 face of the abdomen being red. The radius in some specimens 

 forms an angle with the basal vein of the areolet at their point of 

 union. The cocoons are spun parallel to one another, but not in 

 an even series, on a leaf, and are enveloped in white floss silk. 



The difference in the cocoons may easily be due to the difference 

 in the conditions under which they were spun. The Army-worm 

 being amid the grass, the Microgasters can there most readily 

 attach their cocoons in a mass to the blades or stems, but when 

 emerging from a Sphinx caterpillar they have only the body of 

 their host for a support and each one must take care of itself The 

 Microgasters bred from the cluster of parallel cocoons represented 

 in Fig, 9, and which were referred to in the "American Ento- 

 mologist," vol. i. p. 224, as found on the branch of a 

 dwarf apple tree by Mr. Henry Kleinhaus of Nyces, 

 Penn., agree with specimens oi congregahis bred from 

 aUei^cocoons, Sphinges, except in the second abdominal joint being 

 p'le'twig" '^'^' polished and only slightly punctured, or only finely 



* I have still another Microgaster parasite bred from the Army-worm. It differs from 

 the others in belonging to the genus Microplitis and in being solitary, only a single mag- 

 got deriving nourishment from the partially grown Leucania larva. The specimen is, how- 

 ever, too poor to describe from. 



