37 



Specimens of the affected straws show that a part of this injury was 

 due to Isosoma fritu'i, whose presence could })e detected by the hirval 

 cells in the walls of the straw; also man}' straws were attacked T)}^ a 

 noncell-making- species, the larvte being- in the center of the stems 

 immediate! \^ above the joint. No adults were reared, as the larv?e 

 were supposed to be those of the old hosoina triticl Riley, which is 

 not now known to attack any grain except M^heat. It is therefore 

 impossible to say which of the species whose larva? live in the cen- 

 ter of the stem it was that did the injur}- in these cases. I made 

 everj^ effort to secure material from the fields of rye about Ur1)ana 

 and Champaign, 111., during the summer of 1902, but was unable to 

 find an}- infested straw, and therefore can throw no light upon the 

 identity of the rye-attacking species; but the fact that the one under 

 consideration is known to affect rye in California Avould place it under 



Pir.. 13.— /sosojn/i hiriijrnmt Hdw.: luhilt female, inncli eiiliirgert (after Howard). 



suspicion wherever it oceurs in the eastern States, I judge that it 

 will be very easily confused with other species, and the fact of its 

 infesting cheat would lead to the suspicion that it will l)e found infest- 

 ing other grasses. 



DESCRIPTION. 



"■Female. — Length, 3.7 mm.; expanse, 7 mm. Sculpturing of head, pronotum, and 

 mesonotum as in /. websteri, except that there are sjmrse, large, shallow punctures on 

 the mesoscutellum ; cheeks much fuller than in other species; metanotum as with I. 

 maculatum. Abdomen about as long as thorax; segments 3 to 6 increasing in length. 

 Antenn;e stout, moderately long, very hairy; proportions about as in /. vebsteri. Body 

 not unusually pilose, except face, which is closely covered with short white pile; pro- 

 notal spots very plain, but not large, occupying about one-third of the dorsal aspect 

 of the fore-border of the pronotum. Color black, except for all femoro-tibial knees 

 and pronotal spot. Claw of stigmal club given off some distance from tip, delicate 

 and short." (Howard, Tech. Ser. 2, Div. Ent., U. S. Dept. Agr., p. 16, 1896.) 



