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ON THE SUPPOSED FIRST STAGE LARVA OF LEPTOHYLEMYIA 



COARCTATA, FALL. 



By D. Keilin, D.Sc. 

 (From the Quick Laboratory, University of Cambridge.) 



It has been well known since the studies of Taschenberg (1864-1872) that the 

 larvae of Leptohylemyia coarctata, Fall., attack wheat and rye. The damage due to 

 this fly has been observed many times in almost all European countries, and main- 

 papers have been devoted to its life-history. Of these papers the most important 

 are those of E. Ormerod (1882-1895), S. Rostrup (1905-1911), T. Hedlund (190&- 

 1907), P. Marchal (1909) and finally the recent work of Kurdjumov (1914). 



We owe to Hedlund (quoted by Kurdjumov, p. 25) the most complete account of 

 the development of this fly. According to this author, copulation takes place with 

 this species at the beginning of July. The examination of the ovaria of females 

 captured in the field at different times has led him to the conclusion that the deposi- 

 tion of eggs takes place between the 1st and 22nd of August. Hedlund has also 

 observed that eggs of this fly, which were laid in earth in the breeding vessels at the 

 beginning of August, contained in September a completely formed larva which in 

 December had not yet hatched. 



In this way it seems that he has been able to confirm the supposition of Ormerod 

 and of Rostrup that L. coarctata has only one generation per annum ; that it deposits 

 its eggs towards the end of summer or at the beginning of the autumn ; that the 

 eggs, which are always laid in the earth, hibernate ; and that the larvae do not hatch 

 till the spring. 



These results were accepted by Kurdjumov (1914) in his recent publication on this 

 fly.* According to this author's personal observations the newly hatched females 

 are never sexually mature and they pass the whole summer in this state of immaturity, 

 so that oviposition takes place only at the beginning of the autumn. Kurdjumov's 

 paper contains also the description and the figures of the egg and primary larva of 

 L. coarctata. This is of special interest, because of all the life- history of this insect 

 the part that is most disputed and the most difficult to observe, but which is of great 

 economic importance, is precisely the beginning of the cycle, i.e., the oviposition and 

 the first-stage larva. From his description and figures it would seem that Kurdjumov 

 produces definite data relating to the beginning of the cycle. 



We shall now consider under what conditions this primary larva was discovered by 

 Kurdjumov. 



During the whole summer he kept in his breeding vessels both males and females 

 of L. coarctata. On 28th August all the flies that he had bred were, with one exception, 

 killed by a fungus. All the females which perished had undeveloped ovaries. The 



* The reader is referred to this paper (in Russian) for full references and for a critical 

 examination of many papers dealing with this insect. Kurdjumov, N.V. : Adia genitalis, 

 Schnabl, and Leptohylemyia coarctata, Fall., Reports of the Agricult. Exper. Station of 

 Poltava, Branch of Agile. Entomol., 1914, No. 21, part ix., pp. 1-43. [Abstracted in 

 Rev. Appl. Ent. ii, 1914, p. 250.] 



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