53 



We are assured a midge- fly is this species when it possesses all 

 these characters. But niany flies also pertain to this species which 

 do not fully possess them, some departing from the standard in one, 

 others in another particular, whereby it happens that no one of 

 these characters is constant and found in all the members of this 

 species. All the bright yellow midges which occur in our wheat 

 fields during the latter half of June may be regarded as the wheat 

 midge. 



LIFE HISTOKY. 



The fly or perfect insect makes its appearance in ordinary seasons 

 a little before the middle of June, in the latitude of New York, but 

 its hatching varies with the latitude and the progress of vegetation. 

 A warm' season hastens, a cold season retards insects and vegeta- 

 tion alike. Under ordinary circumstances this fly lives about three 

 weeks, but if the season be wet and the fly numerous it is seen 

 abroad much longer, sometimes until the middle of August. Mois- 

 ture is its life, dryness smothers and suffocates it, consequently it 

 cannot remain upon the wheat heads during the heat of the day, 

 but rests upon the lower part of the stalks until the sun begins to 

 decline, when it returns to its operations upon the heads. On damp 

 cloudy days the insect is as active in the day as at night, and 

 spots shaded by trees, or wheat on low lands, are the most severely 

 injured. If at the time the fly is abroad, depositing its eggs, the 

 weather be extremely dry, the crop escapes; if unusually wet 

 weather prevails, the grain will be severely injured. 



In the deposition of its eggs the only aim of the fly seems to be 

 to place them in some crevice of the headlet where they will be 

 comparatively secure from enemies, and sheltered from the sun and 

 air, which would shrivel them. From the form and character of 

 the ovipositor it is evident that the fly is restricted to crevices for 

 the deposit of its eggs. They are, perhaps, most commonly placed 

 in the little orifice at the summit of the outermost cliatt', but may 

 be found in any narrow opening upon the headlets which the fly is 

 able to discover. Sometimes a single egg is found, but they are 

 usually in clusters of from two to ten. The young larvee appear in 

 about a week after the egg is laid. In whatever situation hatched, 

 they must find their way at once to the germ or kernel from which 

 they derive sustenance. Attaching themselves first at the base of 

 the kernel they afterwards, as they increase in size, usually with- 

 draw farther up the side. The larvae mature in about three weeks 

 and may often be seen descending to the ground as early as July 

 11, while some of the parent flies are still depositing their eggs. 

 Some of the larva throw themselves to the earth with a skip from 

 the beards ; others crawl down enveloped in a pellicle of water ; and 

 still others crawl in a serpentine track till the globule of water in 

 which the larva is moving becomes so large that it is upon the 

 point of running down the straw, when the larva lets go its hold, 

 and is carried to the earth. 



It is a mistake to suppose that only the larvse which go into the 

 ground before harvest live and produce the flies of the following 

 year. Experiments indicate that few if any of the larvae would be 



