The Wheat Midge. Cecidomyia tritici. Kirby.

Fig. II.

1, Floret with larvæ;; 2 to 5, larvæ;, nat. size and mag.; 7 and 8, parts of antenæ, mag.; 9 and 10, perfect insect, nat. size and mag.; 11 and 14, parasite fly, Pltygaster Tipulæ, nat. size and mag.; 12 and 13, parasite, Macroglenes penetrns, nat. size and mag.

In most seasons quantities of these midges—tiny flies—are seen late in the evening flying near wheat fields in the early part of June, just at the time when the wheat ears are beginning to appear. Later on many will be found within the wheat ears, evidently depositing eggs there. These change quickly into maggots which may be seen with their heads thrust into he stigmata of the flowers of the wheat plants. It is supposed by Köllar and some other entomologists that they live upon he pollen after it has been shed from the anthers, but Profesor Henslow considers it more probable that they subsist upon the juices secreted in the ovary; and there can be no doubt that they do suck out the sap from this and the adjacent parts of the flower, thereby hindering the perfect development of the grains. The prejudicial effect of this insect was first noticed in England by Mr. C. Gullet, and described in the Philosophical Transactions in 1772. Mr. Marsham, the Secretary of the Linnæan Society, investigated this subject in the Proceedings of the Linnæn Society in 1796.

Very much injury is frequently occasioned by the Cecidomyia tritici. Curtis speaks of it as very destructive to wheat crops as far back as 1828. Professor Henslow gives instances where ears of corn were found having only very few perfect grains within them, and he quotes Kirby as stating that in a certain field of wheat the loss was equal to a twentieth part of the crop. He also gives an instance of a third part of the crop being lost, in Perthshire. Other observers have found larvae of these midges in almost every ear they have examined in certain fields. Mr. C. S. Read, in his Report on the Farming of Oxfordshire in the Journal of the Royal Agricultural Society, says that in 1858 "the damage caused by the wheat midge was something fearful." More recently it has been very destructive occasionally. In 1883 and 1884 it caused considerable losses in wheat fields in various parts of the country, particularly in Gloucestershire, Wiltshire, and Kent. It is supposed that it was first introduced into this country in Kent, and that it came from France originally, where it is much dreaded. M. Herpin, a distinguished French entomologist, says that it is a native of France. M. Rendu describes it at some length in his Insectes Nuisibles à l'Agriculture, under the head of La Cécidomie desblés. Taschenberg says that it is well known to agriculturists as doing much harm to wheat plants in Germany, while in America it is even more harmful than in England. Professor Lintner remarks that steps have been taken in America for the importation of wheat midge parasites from France in order to check this pest. It is gathered from various reports of entomologists to the Commissioners of Agriculture in Canada that the wheat midge is often very troublesome in that country.

In this last season, 1885, several complaints have been sent as to injury from this insect, and samples have come to hand containing quantities of larvae and showing serious damage. One sample of Square-head from Bedfordshire was especially affected. Samples of Velvet White and Red Lammas, from Kent and Hants, were also much affected. Miss Ormerod, among other affected samples, received one of Essex Wonder very full indeed of larvæ and imperfect grains, and relates that Golden Drop wheat plants growing in an adjoining field were comparatively free from injury.

This midge is also found upon couch grass and upon other grasses in England as well as in France, in Germany, and America. Mr. Carruthers, the consulting botanist of the Royal Agricultural Society of England, reports that he has found its larvae in the heads of meadow foxtail, Alopecurus pratensis, to the considerable injury of the seed.