THE ONION'-FLY : ITS HISTORY, ETC. 173 



OsT. Sacken : Cat. Dipt. N. Amer., 1878, p. 168 (references), p. 258 (note). 



Betuunk : in Ann. Kept. Eut. Soc. Ontario for 1880. (1881), p. 43. 



Meadk : in Entomol. Month. Mag., xix, 1883, pp. 213,218 (as Phorhia cepetorum). 



The ouiou-iiy has long been known to inlerlere seriously with the 

 cultivation of onions. Its ravages had been noticed and recorded both 

 in tliis country and in Europe, long before Bouche, in the year 1834, 

 described ic as infesting onions, and gave to it the scientific name of 

 Anthomj/ia ceparum, which it has since borne up to the present time, 

 and by which it has so often been presented to public notice by ento- 

 mological writers.* It is not known when it was introduced in this 

 country, but it may easily have been brought over at any time, either 

 as larvffi feeding during the voyage, or as pupse, since its pupal transfor- 

 mation often takes place within the plant. It is rather a local species, 

 being very destructive in some localities, and almost unknown in 

 others. It also, like many other of our injurious insects, has its periods 

 of unusual abundance over a broad extent of territory. Thus it is re- 

 corded as having been quite destructive in the Eastern and Middle 

 States in 1854 and again in 1863. 



Its Natural History- 

 There are successive broods throughout the season. The first attack 

 is made as soon as the young seedlings are an inch or two above the 

 ground. The flies are atti*acted to the plants, and deposit their eggs 

 upon the lower part of the leaves, either among them at their base, or, 

 as frequently, along the edge of the lower leaf or slieatli as shown in 

 Fig. 49. Seldom more than a half dozen eggs are deposited on a 

 single plant. 



TJie Eggs. — The eggs are white and smooth, elongate-oval in form, 

 and of a size which admits of their being readily seen by tlie eye, being 

 four-hundredths of an inch long and about one-hundredth broad. In 

 Fig. 47 at a and h they are shown in their natural size and in enlarge- 

 ment. They usually hatch within a week, the time required varying 

 witii the different broods and with the temperature of the season. 



The Larvm. — The young larva, upon leaving the ^g^^ burrows 

 downward Avithin the sheath, leaving behind it a discolored streak 

 to mark its passage. It penetrates the cylindrical root, of which 

 it consumes the interior with the exception of the outer skin. At a 

 later stage of growth of the plant when the bulb has commenced to 

 form, several of ihe larvtB may be found feeding in company. When 



♦According to Professor J. 0. Westwood, Kirby and Spence were the first to apply the 

 specific name to this insect. Reference is made by him {Mag. ISiat. Ilist., vii, p. 425), to 

 ^' Scatopliaija ceparum K. and S., i, 190." This may have been in the first edition of the 

 Introduction to Entomology, to which I liave not been able to refer. Probably no descrip- 

 tion accompanied the name. 



