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XXIII. 



THE LARVA AND PUPARIUM OP THE PRIT-FLY. 



By THOMAS R. HEWITT, A.R.C.Sc.I., 



Research Scliolar in the Royal College of Science, Dublin. 



[communicated by VROFESSOR GEO. H. CARPENTER.] 



(Plate XXVII.) 



[Read May 26. PuljUshed June 18, 1914.] 



This species (Osciiiis frit Linn.) is one of the worst cereal pests in Europe. 

 It is common in Great Britain, and in recent years has been reported as doing 

 considerable damage to cereals in several counties in Ireland. (See Carpenter, 

 1902, 1913.) Accounts of the life-history are given in the memoirs of Bos 

 (1891), MacDougall (1912), and Theobald (1906), referred to at the end of the 

 paper. None of these, however, gives a satisfactory description of the larva, 

 and having material from Cookstown, Co. Tyrone, at my disposal, I have made 

 as full a study as possible of the early stages. I am indebted to the kindness 

 of Dr. Stewart McDougall for mounted specimens of the puparium and very 

 young larva. 



The fully grown maggot (Plate XXVII, fig. 1) measures about 3 mm. 

 long, and "3 mm. in thickness. The body, as is usual among Dipterous 

 larvse, has eleven segments, is legless and fairly uniform in thickness, except 

 at the head region, which tapers slightly. The head region bears two 

 one-jointed papillse or feelers (figs. 1, 2, 3 F) ; below these are two slight 

 prominences, which when highly magnified appear as a number of small 

 outlined areas arranged in the form of a crescent surrounding a circular 

 central area; each area carries a small central spine (fig. 4). These areas 

 appear to be thickenings of the cuticle ; and the spines probably serve as 

 sense-organs. The dorsal surface of the head region bears a number of 

 hook-like spines (fig. 2 Sp.) directed backwards ; and the cuticle is thickened 

 in transverse ridges (fig. 2, r) from these spines towards the mouth. There 



SCIENT. PEOC. R.D.S., VOL. XTV., NO. XXIII. 3 D 



