Feb. 3. 1920 European Frit Fly in North America 467 



This case compares very well with the immense infestation of barley 

 kernels reported by Linnaeus in 1750 (-tj); no doubt both represent 

 extreme instances of this sort of damage. 



Professor T. H. Taylor, of the Department of Agriculture, Leeds 

 University, England, has kindly given the following summary of his 

 observations on the oat fly in England in a letter dated October 6, 191 5.* 



The chief attack is made upon the oat crop. I have seen crops very seriously 

 damaged by the pest. The attack that injures the oat plants most seriously is caused 

 by the first brood appearing in early summer. These flies lay their eggs on the leaves 

 of the young oat com and the larvae bore in the heart of the plant and destroy the stem. 

 The plant thereupon tillers and produces a stimted bunch of yotmg shoots which are 

 practically worthless. The farmers call this condition of the oats "segging." The 

 second brood of flies remains mostly — rbut perhaps not altogether — ^upon the oat crop, 

 and the larvae attack the grains between the glumes. These larvae pupate in situ and 

 the flies (third generation) migrate from the oats to wild grasses, upon which they 

 spend the winter, pupating the following spring and giving rise to the first brood of 

 frit-flies for the new season, thus completing the vicious circle. I have come across 

 isolated examples of frit-fly attacking the stem of wheat and barley, but as I have 

 paid very little attention to these outside attacks I can only say that they appeared 

 to be due to the ordinary /ni. I do not remember to have seen the grains between the 

 glumes of either wheat or barley attacked. 



When the writer's studies early revealed the fact that the American 

 species has a marked distaste for the oat, several lines of investigation 

 were carried out in order to test this relation as fully as possible. 



(i) Wheat, rye, emmer, barley, and oats, sowed in rows in the garden 

 in late spring, were infested in the order given, wheat much the worst, 

 oats hardly at all. Oats sowed in the garden on August 25 were taken 

 up and placed in a cage on September 20, when they were about 10 inches 

 high and very thrifty. They had occupied a rather dense row about 25 

 feet long. In this cage only one specimen of Oscinis frit emerged, on 

 October 16. A control cage of wheat sowed at the same time and caged 

 at the same time yielded 68 adults of O. frit — 12 on October 5, 20 on 

 October 13, 8 on October 16, 20 on October 22, 3 on October 27, and 5 

 on November i . 



(2) Eight cages were started in which pairs of Oscinis frit were con- 

 fined on young oat plants. Three eggs were laid in two cages, but no 

 adults developed. 



(3) In order to learn whether the American spe-^ies is able to feed upon 

 the oat stem at all, on September 10 and 13, 1915, 29 larvae were dis- 

 sected out of young wheat stems and placed on similar young oat stems 

 in vials, as described under "Methods," p. 459, except that the food 

 plant was changed. The results are shown in Table IV. 



In most instances the larvae which did not enter lived about a week, 

 crawling actively on the glass much of the time. 



' Professor Taylor disclaims any attempt to identify the species of the insect; specimens sent by him 

 at the same time, however, seem indistinguishable from Oscinis frit as identified by Professor Bezzi and 

 G. Strobl. 



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