49 



others cemented to the stems just at the margin of the sheath, while still 

 others were placed along the edge of the sheathing base of the leaf, 

 sometimes being thrust under the edge." This agrees with mj' own 

 observations and is doubtless the usual method of oviposition, as the 

 main object on the part of the female is to place the eggs where the 

 3'^oung larvse will the most easiW reach the tender, juicy stem as soon 

 as possible after escaping from the egg, and is probably true in the 

 case of grasses as well as of grain. 



METHOD AND NATURE OF ATTACK. 



Both Doctor Lintner and Doctor Forbes have endeavored to indicate 

 this bv the selection of explanatory common names for this insect. The 

 former, disregarding Fitch's name. American Meromyza, as too tech-' 

 nical, and having observed the larva? in the full-grown straws only, 

 gave it the name of the "wheat-stem maggot," while Doctor Forbes, 

 having tirst encountered the iarv» in the bulbous lower stem in early 

 spring, gave it the name of the "wheat-bulb worm," on account of 

 its resemblance to the " wheat- l)ulli maggot" {Ilylemyla cvarctata) of 

 England. It is really a maggot and atf'ects the stems of the plants 

 which it infests, besides being the largest maggot of this kind at 

 present known to attack the stems of grain in this manner in this 

 country; hence, in order to distinguish it from other smaller stem 

 maggots, I have here termed it the " larger wheat stem-maggot." 



The larva has no jaws or mouth, but a couple of hook-shaped 

 appendages by which it tears the plant and feeds from the juices, the 

 cavity made by this destruction of the stem being filled by a pomace- 

 like mass in which the larva is to be found. The effect on the plant 

 is shown b^' the accompanying illustration (tig. 14, d). In young 

 plants the central spindle-shaped enfolded leaf is killed, precisely as 

 with attacks of Oscinis larva% the detached portion turning first yellow 

 and later brown, then shriveling up and dying, leaving the outer 

 lower leaves uninjured. In Hessian -fly attacks this spindle-shaped 

 leaf is absorbed and does not appear at all in young wh(^at in autunm, 

 so that there need never be any confusion of the work of these two 

 insects in fall wheat, and the effect on the full-grown straws is even 

 more easily distinguishable. When attacked by the maggots of this 

 species the fully grown straw withers at the upper joint and all that 

 portion of the stem including the head, the sheath excepted, changes 

 to a whitish color, the remainder of the plant, including the upper 

 sheath, continuing uninjured and of the usual green color. The Hes- 

 sian fly never affects the full-grown straws in this manner and the 

 lesser wheat stem-maggot does so but rarely, so that the presence of 

 these maggots in the straw can be easil}^ detected shortly prior to 

 harvest by their whitened color from the upper joint upward. The 

 larv« are within the stem and not outside and under the sheath, as 

 7327— No. 42—03 4 



