NO. 2349. REVISION OF NEARCTIC APANTELE8—MVESEBECK. 487 



miners but a short time. Evidently all that is necessary in this last 

 case is that the host larA^a should be a miner in the stage which the 

 parasite prefers for oviposition. General similarity of appearance 

 and close resemblance of habit apparently suffice to invite attack 

 by a particular species of Apanteles. 



Some species are solitary, while' many others are gregarious, in 

 the latter case sometimes as many as 100 or more individuals issu- 

 ing from a single host. There seems, however, to be no correlation 

 at all between this biological characteristic and any structural char- 

 acters which might divide the genus into well-marked groups. The 

 difference between the cocoons is often very striking. In color they 

 vary through yellow and buff to dark brown and dark gray; and, 

 in the case of the gregarious species, differ widely as to arrangement 

 and the extent to which they are surrounded by loose silk. 



As natural control agents of injurious insect pests many species 

 of Apanteles assume an important role. Many of our most common 

 injurious species are to a large extent held in check by parasites af 

 this group. Amiong these may be mentioned Pieris rapae Linnaeus, 

 the cabbage butterfly, also the gipsy and the brown-tail moths, and 

 many cutworms, including the army worms. Because the genus 

 contains species of widely diverse habits and biologies, the larvae 

 of no considerable group of Lepidoptera are free from their attacks. 



KEY TO THE SPECIES OF APANTELES. 



1. Propodeura with a distinct areola, which is usually margined by strong 



carinae; if not sharply outlined, then tlie first abdominal tergite has a 

 more or less distinct median longitudinal depression on the apical half, 

 the second tergite is short, transverse and broader at apex than at base, 



and the ovipositor is at least half as long as the abdomen 2. 



Propodeum without an areola, often with a median carina from base 

 to apex ^2- 



2. Abdomen very short and broad, and strongly depressed; the three basal 



abdominal tergites large, occupying practically all of the dorsum of the 

 abdomen, and entirely rugose; propodeal areola very large and broad 

 diamond-shaped, sharply margined; ovipositor sheaths subexserted. 



1. hucculatricis, new species. 



Abdomen never so short and broad and depressed, and never with the 



three basal abdominal tergites wholly rugose and occupying almost the 



entire dorsum of the abdomen 3. 



3. Face strongly rostriform, the malar space long; ovipositor sheaths as 



long as the abdomen 4. 



Face normal- 



.6. 



4. Posterior femora black 2. 7)fl«7fsi Viereck. 



Posterior femora dark testaceous 5. 



5. Propodeum and first abdominal tergite coarsely rugose, the propodeal 



areola defined by very strong ridges; second abdominal tergite uni- 

 formly roughened 3. crassicornis (Provancher). 



Propodeum and first abdominal tergite not so coarsely roughened, the latter 

 only finely rugulose on the apical half; second tergite almost entirely 

 smooth and shining 4. dolichocepJialus, new species. 



