33(^ 



AN ECONOMIC ENTOMOLOGY. 



Lt;gs and larva of J''.piilapHS 

 scabei, mucli enlarged. 



that especial purpose. P'ortunately, the measures used to prevent 

 the scab due to the fungous disease seem to destroy the insects as 

 well ; hence the method of distinguishing 

 between the two is not important. 



In the family Cecidoniyidce, containing 

 the midges, or "gall-gnats," we find the 

 most injurious species of the order. They 

 are also mosquito-like in appearance, but 

 usually very small, with very long an- 

 tennae, which in the males are clothed on 

 each joint with whorls of fine hair. The 

 larvae are ovate, quite broad, and a little 

 flattened, the segments well marked, and 

 the apparent mouth parts formed in 

 many species by a peculiar horny pro- 

 cess which is known as the "breast- 

 bone," from its situ;ition. The species 

 are numerous, and the larval habits and 

 life histories are very diverse. In most 

 cases growing vegetable tissue is the 

 food, and, ao a rule, a more or less marked gall-like swelling 

 indicates the location of the larva. 



The most widely known species is the "Hessian-fly," CcciJ- 

 omyia dcsfnicior, one of the most serious enemies of wheat, 

 actually inhibiting its cultivation in some localities. The adult 

 is rather large for this family, smoky brown in color, and appears 

 late in the season, usually after the wheat is well above ground. 

 Eggs are laid on the young plants, and the larvae w^ork their way 

 into the stem at or near the surface, causing a slight gall or swell- 

 ing and a deformity in plant growth. When winter sets in full 

 .'-ize has been reached, and the "flaxseed" stage is entered 

 upon, — so called because of its superficial appearance, though it 

 is really the brown, dry, and hardened larval skin itself. In 

 spring the pupa is formed, and soon afterwards the adult appears, 

 ready to oviposit again in the now rapidly growing wheat. Tlie 

 flaxseed stage is again formed low down in the stalk before har- 

 vest, so that it usually remains in the stubble when the grain is 

 cut. There it rests until the new wheat sprouts. in fall, though 

 flies may be found all summer, and it is. more than likely .that 



