54 CORN AND GRASS. 



Mr. Gibb wrote : — " A great many of the common farm pests have 

 shown themselves again this spring, but (except in the case of Frit 

 Fly, which did great hurt during the dry spell about six weeks ago, 

 when I counted in different places from 20 to 40 plants of Oats 

 destroyed per square yard) recent rains have now greatly effaced this 

 damage." 



The figures at p. 51 give a good idea of the appearance of the 

 maggot and chrysalis-case when moderately magnified. When much 

 magnified it can be seen that the maggot has a branched spiracle on 

 each side near the head, and at the tail it has two projecting wart-like 

 spiracles. When the jmpariuni, or chrysalis-case is still newly formed, 

 the branched spiracle near the head end is still very observable when 

 magnified. The two wart-like spiracles at the tail extremity are 

 slightly indicated in the figures, both of maggot and chrysalis. 



In this country we have now found that the three successive 

 generations of the fly, namely, early summer, late summer (in the Oat 

 heads), and autumn or winter again (like the first attack of the year 

 in the young plants), are, or may be, present, though the two latter 

 appear practically, as Corn pests, of little account. But what this 

 attack is in favourable circumstances is excellently given by Dr. J. 

 Eitzema Bos, Prof, at the Royal Agricultural College, Wageningen, 

 Netherlands,* in great detail in his observations, published in the 

 course of last year (1891), and from them I extract some points which 

 may help us both in our investigation, and in practical treatment. 



" The Frit Fly has commonly three generations in the course of 

 the year, and the maggots live according to the time of year in the 

 lower or higher part of the stem, or in the not yet entirely developed 

 ears of graminaceous plants, — in wild or pasture grasses, as well as in 

 cultivated kinds of Corn." ..." The Frit Flies pass the winter 

 in pupal state." ..." From the hybernated pupae the Frit Flies 

 usually develop at the end of April. Tliey then infest, in their skipping 

 or dance-like flight, both various kinds of grasses, and the summer 

 Corn (summer Rye, summer Wheat, Barley, and Oats). It is necessary, 

 however, that the Corn should not be far advanced in its growth ; the 

 stem must still be entirely hidden in the leaf sheaths, and also must 

 still be exceedingly small." — (J. R. B.) 



The above extracts carry us forward to the conditions of which we 

 know the history only too well here. We find (when attack is troubling 

 us) that the Oat plants during June show signs of mischief within, and 

 on examination the white Frit maggot is found to have destroyed the 

 centre of the shoot. According to date it may be lying there as a 



* See ' Tierische Schadlinge unci Nutzlinge,' von Dr. J. Eitzema Bos, p. 29, 

 Berlin, 1891. 1 give the quotations in tianslation.^ED. 



