ART. 2. ICHNEUMON-FLY GENUS METEORUS MUESEBECK. 7 



of approximation of the ventral margins of the first abdominal tergite 

 (several types of which are illustrated) is relatively ver}^ constant and 

 will be found extremely helpful in identifying specimens of this genus. 

 Other useful characters are found in the wings ; while there is always 

 more or less variation here, as used in the key these characters will 

 probably be found good. There is some variation within species in 

 the size of the ocelli; those of the males are as a rule a little smaller 

 than in the female, and even in the same sex slight variations occur; 

 yet, considerable reliance can be placed upon this character, as also 

 upon the length of the malar space. The number of antennal seg- 

 ments varies within quite definite limits, and to a certain extent is 

 dependable for the separation of species. In the case of the females 

 the length of the ovipositor sheaths helps greatly in making identifi- 

 cations. Color and sculptural characters are the most variable of 

 all, and must be used with much care, but where they have been 

 employed in the following key they are apparently of considerable 

 value. 



KEY TO T^E NORTH AMERICAN SPECIES OF METEORUS. 



1. Radiellan cell distinctly broadening toward apex and divided by an indistinct 



cross- vein; second abscissa of radius usually longer than second intercubitus. .2 



Radiellan cell narrowing or at least not broadening, toward apex and with no 



indication of a cross- vein; second abscissa of radius never longer, 



usually shorter, than second intercubitus 6 



2. Mesopleura entirely smooth and polished; antennae with about 30 segments; 



posterior tarsi brownish 1. levis, new species. 



Mesepleura closely punctate or finely rugulose on lower half; antennae with 

 37-50 segments 3 



3. Ovipositor sheaths nearly as long as the abdomen; body color deep ferruginous, 



the thorax, especially in the sutures, and often base and apex of abdomen, 

 tinged with blackish; antennae brown, except scape beneath; posterior tibiae 

 black on apical half; posterior tarsi white; nervellus decidedly longer than 



lower abscissa of basella 2. niveitarsis (Oresson). 



0^dposito^ sheaths only half as long as the abdomen; otherwise not agreeing with 

 all the above characters 4 



4. Lower abscissa of basella about equal to nervellus; ocell-ocular line a little longer 



than greatest diameter of an ocellus; antennae testaceous; posterior tarsi pale 



yellow or whitish 3. pallitarsis. (Cresson), 



Lower abscissa of basella much shorter than nervellus; ocell-ocular line no longer 

 than diameter of an ocellus; antennae and tarsi variable 5 



5. Length about 10 mm.; antennae with 43-47 segments; posterior tarsi whitish 



4. maximus, new species. 



Length 5-6 mm.; antennae with 38-42 segments; all tarsi testaceous or fuscous 

 5. reticulatus, new species. 



6. Petiole of abdomen with two deep fossae dorsally anterior to the spiracles; ventral 



margins of first abdominal tergite usually widely separated, at most barely 

 touching and then diverging again; mesonotal lobes prominent and sharply 



defined 7 



Petiole of abdomen without fossae dorsally; ventral margins of first abdominal 

 tergite meeting, although sometimes for only a short distance; mesonotal lobes 

 often not so well defined 19 



