336 INJURIOUS INSECTS, WITH TREATMENT 



Gall-fly {Contarinia violicola). — The adult is a minute mos- 

 quito-like fly. The whitish or yellowish maggot feeds in folds 

 of the opening leaves, which become deformed, turn brown, and 

 die. 



Treatment. — Fumigation is practically of no value. Thorough 

 hand-picking as soon as any sign of injury is noticed. Do not 

 let the pest become established in a house. 

 Red-spider (Tetranychus bimaculatus) . — Minute mites which 

 cause the leaves to turn paler and become yellowish. 



Treatment. — On greenhouse violets there is nothing better than 

 a stiff spray of clear water so applied as not to drench the beds. 

 Repeat the spraying once or twice a week. See p. 304. 

 Wheat. Hessian-fly {Mayetiola destructor). — A small maggot in- 

 festing the plant between the leaf sheath and the stem. When 

 full grown they transform to the puparium or " flaxseed " stage. 

 Preventives. — Crop rotation, destruction of all volunteer wheat. 

 Burning stubble where practicable. Late sowing as follows : — 

 After September 1 in northern Michigan ; September 20 in south- 

 ern Michigan and northern Ohio ; October 1 in southern Ohio ; 

 October 10 to 20 in Kentucky and Tennessee ; October 25 to 

 November 15 in Georgia and South Carolina. (Bureau of Ento- 

 mology.) 

 Joint- WORMS {Isosoma spp.). — Small yellowish larvae found in 

 the straw, causing hard knots or galls. 



Preventives. — Crop rotation. Heavy use of fertilizer to give 

 a rapid growth. Burning of stubble wherever practicable. 

 Chinch-bug. — See under Corn, p. 314. 

 Willow. Willow- worm (Euvanessa antiopa). — Larva, nearly two 

 inches long, black, feeding upon leaves of willow, elm, and 

 poplar ; two broods. 

 Remedy. — Arsenicals. 



