106 



CORl^ AND GRASS. 



on screenings in which Cockle-galls were mixed, and which 

 would consequentl}^ be almost certainly infested with the Gall 

 Eel worms. 



Wheat-bulb Fly. llylcwyia auirctnta, Fulleii. 



^EXi^kTj 



Wheat-bulb Fly (Hylemyia coarctata), magnified, and lines showing nat. size ; 

 maggots and chrysalids, nat. size and mag. ; mouth-apparatus, and extremity 

 of tail, with tubercles, mag. ; infested plant. 



The attacks of the maggots of the Wheat-bulb Fly and those 

 of the Frit Fly (noticed at p. 73), are much alike so far as 

 method of injury is concerned. In both cases the injury to 

 the plants is caused by the maggot feeding within the young 

 stem, and thus causing the death of the infested shoot from 

 the joint effect of the gnawing of the maggot and the con- 

 sequent decay of the attacked part ; and the two kinds of 

 whitish maggots also look very similar to the naked eye, but 

 when examined with even a moderately powerful glass the 

 differences may be clearly distinguished. The Wheat-bulb 

 maggot thus seen is whitish, legless, cylindrical, and somewhat 

 lessened towards the head end, which is furnished with two 

 black mouth-hooks. The tail extremity is furnished above 

 Avith two black spots, which are the sjnracles (or breathing- 

 pores), by which air is drawn into the very observable traclicce 

 (or air-tubes). Beneath, that is at the lowest part, the tail 

 segment projects, and ends in tAvo squarish-ended teeth with 

 flattened edges placed centrally, with one pointed tooth, and 

 sometimes more on the outside of the central square pair. 

 When seen with a higher power the teeth appear as fleshy 

 projections (see figure 1), and the ends of the two central 



