FLY IN WHEAT. 



PLY IN WHEAT. 



only become flies next year at the season when 

 the corn is in blossom. Fortunately, nature 

 has in this case provided another still smaller 

 parasitic insect, allied to the family of Ichneu- 

 mons, to keep the midge also within its pro- 

 per bounds. Mr. Kirby, who first made us ac- 

 quainted with the natural history of this insect, 

 calls the parasite Ichneumon Tipula. It is a spe- 

 cies of the genus Platygaster of Latreille, be- 

 longing to the family Prodotrupirla: 



Mr. Gorrie states that, from the experiments 

 which he made in the season 1831, the variety 

 of wheat cultivated under the name of Cone 

 wheat (Triticum turgidum, PI. 2,d), is not liable 

 to the attacks of the fly. (Quart. Journ. of dgr. 

 vol. iii. p. 639.) Mr. Shirreff (Ibid. p. 305), also 

 considers the Polish wheat (T. Polonium, PI. 2, 

 e), to be in a measure secure from its attacks. 



The ravages committed by the wheat-fly in 

 Scotland are sometimes very extensive. It is 

 stated by Mr. Shirreff, that throughout the whole 

 of East Lothian, during the years 1827, 1828, 

 1829, and 1830, the fly injured the wheat crop 

 to the amount of 30 per cent. Should the fly 

 abound in this proportion throughout the king- 

 dom in successive years, the loss to the com- 

 munity would be incalculable. Mr. Gorrie 

 seems to think that the wheat-fly maggot might 

 be so buried as not to be able to work their 

 way up through the superincumbent soil ; if, 

 in ploughing in the wheat stubble, a scarifier 

 or skimmer were fixed upon the beam before 

 the coulter, so constructed as to lay about an 

 inch of the surface in the bottom of the furrow. 

 There is Miother kind of fly or midge (Tipulti 

 cerealis, Samer), which is particularly injurious 

 to spelt (a kind of dwarf wheat) and barley. 

 (Kollar on Insects injurious to Agriculture. Quart. 

 Journ. of Jlgr. vol. ii. p. 3; Westwood on Wheat 

 Flies, in Gard. Mag. vol. xiii. p. 289.) 



An insect resembling the European wheat- 

 fly in its habits, and known, in its maggot 

 form, by the name of " the grain-worm," has 

 been observed for several years in the north- 

 ern and eastern parts of the United States 

 and in Canada. (See PI. 2, i, where the maggot 

 and fly are represented as highly magnified.} " It 

 seems," says Dr. Harris, "to have been mis- 

 taken by some for the grain-weevil, the Angou- 

 mois grain-moth, and the Hessian fly, and its 

 history has been so confounded with that of 

 another insect, also called the grain-worm in 

 some parts of the country, that it is difficult to 

 ascertain the amount of injury done by either 

 of them alone. The wheat-fly is said to have 

 been first seen in America about the year 1828, 

 in the northern part of Vermont, and on the 

 borders of Lower Canada. From these places 

 its ravages have gradually extended in various 

 directions from year to year. A considerable 

 part of Upper Canada, of New York, New 

 Hampshire, and of Massachusetts has been 

 visited by it; and, in 1834, it appeared in 

 Maine, which it has traversed, in an easterly 

 course, at the rate of 20 or 30 miles a year. 

 The country over which it has spread has con- 

 tinued to suffer more or less from its alarming 

 depredations, the loss by which has been found 

 to vary from about one-tenth part to nearly the 

 whole of the annual crop of wheat; nor has 

 the insect entirely disappeared in any place 



till it has been starved out by a change of agri- 

 culture, or by the substitution of late-sown 

 spring wheat for the other varieties of grain. 

 Many communications on this destructive in- 

 sect have appeared in the Genesce Farmer and 

 in the Cultivator, some of them written by the 

 late Judge Buel, by whom, as well as by the 

 editors of the Yankee Farmer, rewards were 

 offered for the discovery of the means to pre- 

 vent its ravages. Premiums have also been 

 proposed for the same end by the Kennebec 

 County Agricultural Society, in Maine, which 

 were followed by the publication in the Maine 

 Farmer of three "Essays on the Grain-Worm," 

 presented to that Society. These essays were 

 reprinted in the 17th volume of the New Eng- 

 land Farmer, wherein, as well as in some other 

 volumes of the same work, several other arti- 

 cles on this insect may be found. 



"The American wheat-insect, in its winged 

 form, has not yet fallen under my notice. It is 

 stated by Judge Buel, Mrs. Gage, and others, 

 to agree exactly with the description of the 

 European wheat-fly (Cecidomyia fn'/tri), being 

 a very small, orange-coloured gnat, with long, 

 slender legs, and two transparent wings, which 

 reflect the tints of the rainbow. Immense 

 swarms of these orange-coloured gnats infest 

 fields of grain towards the last of June. While 

 the sun shines they conceal themselves among 

 the leaves and weeds near the ground. They 

 take wing during the morning and evening twi- 

 light, and also in cloudy weather, when they 

 lay their eggs in the opening flowers of the 

 grain. New swarms continue to come forth 

 in succession, till the end of July; but Mr. 

 Buel says that the principal deposit of eggs is 

 made in the first half of July, when late sown 

 winter-wheat and early sown spring-wheat are 

 in the blossom or milk. The flies are not con- 

 fined to wheat alone, but deposit in barley, rye, 

 and oats, when these plants are in flower at the 

 time of their appearance. The eggs hatch in 

 about eight days after they are laid, when the 

 little yellow maggots or grain-worms may be 

 found within the chaffy scales of the grain. 

 Being hatched at various times during a period 

 of four or five weeks, they do not all arrive at 

 maturity together. Mrs. Gage informs me that 

 they appear to come to their growth in 12 or 

 14 days. Specimens of these maggots which 

 she has sent to me were found to agree, in 

 every respect, with the descriptions and figures 

 of those of the European wheat-fly. They do 

 not exceed one-eighth of an inch in length, and 

 are not provided with feet. From 2 to 15 or 

 20 have been found within the husk of a single 

 grain, and sometimes in every husk in the ear. 

 After a shower of rain they have been seen in 

 such countless numbers on the beards of the 

 wheat, as to give a yellow colour to the whole 

 field. These insects prey on the grain in the 

 milky state, and their ravages cease when the 

 grain becomes hard. They do not burrow 

 within the kernels, but live on the pollen and 

 on the soft matter of the grain, which they pro- 

 bably extract from the base of the germs. It 

 appears, from various statements, that very 

 : early and very late wheat escape with compa- 

 ratively little injury; the amount of which, in. 

 , other cases, depends upon the condition of the 



491 



