178 

 The species may be characterized as follows : 



9 Black ; basal joints of the maxillary palpi, large spot on mandibles, two spots 

 beneath anterior -wings, membranous regions of thorax, small spot on lower poste- 

 rior edge of dorsum of first segment, larger one on second segment, band, dentate on 

 basal margin, on apical half of dorsum of third, fifth, and sixth segments, and more 

 or less of the lower and apical margin of the remaining segments, lemon yellow. 



Legs black, slender; spot on posterior coxse above, upper side and tip of femora, 

 yellow; tibije and tarsi reddish yellow except tips of posterior tibite and their tarsi, 

 which are brownish ; last joint and claws of middle and anterior tarsi also brownish. 



Antennse 20-21 jointed, longer than head and thorax, slender to joints 7, beyond 

 which the articles are shorter and thickened. 



Wings slightly smoky ; veins brown except costal and margin of stigma, which 

 are yellowish ; a small infuscated spot at base of discoidal vein; second recurrent 

 vein joins the third submarginal cell near the base of the cell ; cross veins of lanceo- 

 late cell slightly curved arid oblique. 



Abdomen not much longer than head and thorax, strongly compressed laterally. 



Length, 9-11 mm. 



Exp. al., 16-19 mm. 



(? Smaller and more slender than the 9; abdomen less compressed; antennie 18-21 

 jointed. Coloration as in 9 except a large spot on the clypeus, one just below the 

 eyes in front, the entire pectal region of the thorax, and the posterior margin of the 

 third, fifth, and remaining ventral segments, which are lemon-yellow. 



The under side of the coxse, troclianters, and femora, including the apex of the 

 latter above, are lemon-yellow ; the tibise and tarsi are as in the case of the 9 • 



In some specimens the femora are entirely yellow or with a narrow black line on 

 the anterior pair above, and the yellow baud on the third ventral segment is occa- 

 sionally obsolete. 



Length, 8-9 mm. 



Exp. al., 1.5-17 mm. 



Habitat: Santa Clara County and Santa Cruz Mountains, California, 

 Nevada, and Montana. 



Described from 24 females and 14 males, of which 25 specimens from 

 California were bred by Mr. Koebele, and 13 from Nevada and Montana 

 were collected. 



The economic importance of this insect arises from the fact that it 

 may be expected at any time to abandon its natural food-plant in favor 

 of the small grains, on which it can doubtless successfully develop. 

 Such changes in the food-habits of our native insects are constantly 

 occurring, to the great detriment of our Agriculture, as is illustrated by 

 the attacks of the Nematus and Dolerus species on wheat, already de- 

 scribed — these insects unquestionably normally affecting wild grass. 



PABASITES AND REMEDIES. 



Parasites. — A number of parasites have been found to attack the Saw- 

 fly larvfe studied. Of these two were reared from Nematus, Lampro- 

 ?iofrt/n'</i<?rt Cr., and an undetermined form (not found), and an unde- 

 termined Ichneumonid (not found) from the DoJeruslnvxdd, described as 

 form three. 



On one of the larvfe of Dolerus sp. (form 4) occurred three parasitic 

 \c\x\'Xi {Euplectrus f %\).) attached externally to the dorsum of the first 



