has been made to study its occurrence in the spring-wheat-growing 

 sections of Maine. While its al)sence in some parts of the country 

 between the Platte River, in Nebraska, and the Canadian ])oundar3^ 

 line might be attributed to a lack of its food plant, this will not hold 

 in southwestern Kansas and Oklahoma, as in those localities it seems 

 to suddenly terminate in the midst of a wheat-growing section, and 

 where this grain has been cultivated for at least twenty years. Strange 

 as this may at first appear, Doctor Merriam, of the Biological Survey, 

 informs the writer that he finds several parallel cases in the distril)u- 

 tion of some of the smaller mammals. 



FOOD PLANTS. 



While the female fly will often deposit her eggs on grass, or even 

 weeds, the larvpe, so far as known, survive only on wheat, barley, and 

 rye, proportionately in the order mentioned. From time to time 

 •'flaxseeds'" closel}' resembling those of this insect have been observed 

 on the stems of several native grasses, but adults reared from them 

 have not been considered as belonging to this species, owing to sup- 

 posed structural difl'erences, and no experiments have been made to 

 ascertain whether or not it is possible for larvse of the Hessian fly to sur- 

 vive on these grasses. Doctor Forbes some years ago failed to induce 

 the insect to breed in either redtop, bluegrass, foxtail, or orchard 

 grass — species on which "flaxseeds" had, however, not been found. 



Flaxseeds resembling those of Hessian fly have been found on El\^- 

 mus, Agrostis, Bromus, and Agropyron, in California, by Mr. Koe- 

 bele, and on the latter also in Indiana. b\' Mr. W. J. Phillips, a field 

 agent of this Bureau. Besides, Doctor Lindeman found similar flax- 

 seeds on timothy and Acjropijrtm repenx in Russia. 



EFFECT OF LARV.E ON THE PLANT. 



The effect of the larvae on a young wheat plant is very marked and 

 becomes observable soon after the 3'oung reach the stem under the 

 sheath. Once he has observed it, any farmer can readih^ detect an 

 infested plant, or a single infested tiller may })e as readily detected in 

 a cluster without taking the trouble to remove the plant from the 

 ground. 



For the purpose of comparison, illustrations are given of an unin- 

 fested young plant (fig. '.») and an infested 3'oung plant (flg. lo). An 

 uninfested plant is of a more slender growth, the green color is lighter, 

 with a slight tinge of yellow, the stems are more or less visible, and 

 the central unfolding leaf is present. The whole plant is inclined to 

 droop and the tillers spread out and cover the ground. An infested 

 plant is without stem and the leaves are broader, usualh' shorter and 

 of a deep bluish-green color, somewhat resembling those of oats. The 



