358 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



ster has been able to witness the female in the act of ovipositing, and 

 from specimens received from him we have been able to fully verify the 

 conclusions that we previously came to. The matter is of no Slight 

 economic importance, as already shown by Harris, Fitch, and Walsh • 

 for, on the assumption that the genua is parasitic, it will be manifestly 

 unwise to burn the stubble in which many of the larva? hibernate, or to 

 burn the straw after the grain has been harvested, since in such straw 

 there also remain a large number of hibernating individuals. If, how- 

 ever, as it is now abundantly proved, the genus is phytopliagic, these 

 measures at once acquire importance as means of averting future 

 injury. 



Mr. Webster's observations have been made, not only upon tritici 

 Eiley, but, as will be seen from his report, also upon another species of 

 larger size. This we have recently described under the above name, in 

 the December (1884) number of the Bulletin Brooklyn Entomological 

 Society (Vol. VII, p. Ill) from which we reproduce the description : 



Isosoma grande n. sp.— Fern a le— Length of body 4.2 mn ', expanse 7.6 mm . An- 

 tennas rather more sleuder and less clavate than in tritici and but half the length of 

 thorax. Thorax with the mesonotum slightly more rugulose; wings larger and less 

 hyaline than in the winged specimens of tritici, the veins extending to outer third, the 

 submarginal nearly four times as long as marginal; legs with the femora less swollen. 

 Abdomen not so long as thorax, stouter than in tritici, ovate-acuminate, approaching 

 typical Enrytoma. Less hairy than tritici, especially about the legs, the hairs of ab- 

 domen being less numerous, less regular, and shorter. Coloration similar to that of 

 tritici, but brighter and more highly contrasting, the pronotal spot larger and brighter 

 yellow, the pedicel of antennas yellow and the femora with a definitely limited sub- 

 oval, yellowish spot below, near the tip, extending two-fifths the length of femur on 

 front pair, smaller on middle pair and still shorter and less definite on posterior pair. 



Larva. — Greenish-yellow in color. Average length, 6 mm ; otherwise of same propor- 

 tions and structure as in tritici. 



Pupa. — Average length 5 ,D,n . Except in larger size and ample wing-pads undis- 

 tinguishable from that of tritici. 



Described from twenty-four females, reared from wheat-stems in June, and taken 

 by Mr. F. M. Webster at La Fayette, Ind. * * * Its larger size, stouter build, 

 aside from the other characters mentioned readily distinguish it, however; while 

 from hordei Harris, vitis Saunders, and elymi French, it is still more readily dis- 

 tinguished. 



The figures which we have prepared (Plate VII, Figs. 2, 3; and Plate 

 VIII, Figs. 3, 4) very well illustrate the mode of oviposition, and the 

 larval, pupal, and adult characters. The oviposi tor is thrust in an almost 

 straight line through the wall of the straw and reaches to the heart or 

 pith, without, however, penetrating it. The length of the inserted parts 

 generally exceeds l mui , the entire length of the ovipositor being about 



i.6 mm . 



The egg, as carefully studied in females that were ovipositing, is of 

 the ordinary ovoid form, but characterized by a pedicel variable in 

 length but generally twice as long as the bulbous or ovoid portion. 

 Its apical end is also furnished with a distinct hook, the function of 

 which is, in all probability, to hold it in the plant tissue while the ovi- 

 positor is being withdrawn. 



It may be here stated as an interesting fact that of the specimens so 

 far reared both of tritici and grande all are females, and whether or not 

 there is any dimorphic relationship between these two forms is a ques- 

 tion which future observations alone can decide. The probabilities 

 are, however, that there is no connection between them; for, on the as- 

 sumption that they represent alternate generations, we should expect 

 the one or the other to comprise both sexes. 



