43 



myza maggots do not turn brown or "chestnut colored," and those of 

 the Hessian fly, even if it were known to occur in America at that 

 early date, do not eat off the stems. As early as 1822 Mr. James 

 Worth, of Bucks County, Pa., seems to have reared these flies from 

 maggots attacking wheat. 



It is therefore probable that as the area of cultivation increased 

 in this country these insects have gradually transferred their atten- 

 tion from grass to grain as a matter of necessity, and though more or 

 less numerous every year in the grain fields, they become excessively 

 so when the grass conditions are less favorable than those of the grain; 

 but the grasses are a continual source of supply from which tlie grain 

 fields are colonized. These interrelations may be more or less cur- 

 tailed })y the farmer with but little expense. 



THE GREATER WHEAT STEM-MAGGOT. 



{Meromyza americanu Fitch. Fig. 14.) 



PAST HISTORY OF THE INSECT. 



This is in all probability an insect native to the far South, as it 

 occurs in Mexico and northward over the entire United States and far 

 into British America, its food plants, before the advent of the Cau- 

 casian farmer, being the wild grasses. The fly was described in 1856 

 under the name here applied, ))ut without definite proof of its attack- 

 ing grain further than that it was collected in wheat fields and closely 

 resembled the European species Mei'omyza saltatrix Linn, There is 

 now, however, considerable evidence of its having attacked growing 

 wheat at least as early as 1822 in Peimsylvania" and in 1845 in Michi- 

 gan.^ The evidence furnished by Mr. James Worth, of Bucks County, 

 Pa., indicates that three broods were observed, as he calls attention to 

 the attacks of " a little worm found in the lower part of the stalks of 

 wheat and rye in spring and fall and about the joints in Juiie." Of 

 these larvro he says that "some were pale yellow, with brown spots 

 about the mouth," which would imply that they were those of some 

 species of Isosoma; but he further states that one kind was found in 

 volunteer wheat, which the Isosomas do not attack, and their larvae 

 are not found in the plants in fall, and in case of only one, with a 

 possibility of another species, are they to be found in the plants in 

 spring. While Mr. Worth evidently was not able to separate the 

 different species of the larvae found in growing grain, his careful 

 descriptions and exactness in locality and dates are exceedingly val- 

 ua})le and enable those familiar with the forms of which he writes to 

 recognize them with reasonable clearness. Hence we are left with 

 little doubt that he observed the larvas of Isosoma and Meromyza 



"The American Farmer, vol. 4, p. 394; Memoirs Perm. Agl. See, Vol. 1, p. 165. 

 & Prairie Farmer, Sept., 1845, p. 216. 



