178 [August, 



REMARKS ON THE BIOLOGY OF CHARAEA8 GRAMINIS L. 



BY A. D. IMMS, M.A., D.Sc. 

 Reader in Agricultural Entomology, Manchester University. 



During the month of June 1917, I had occasion to investigate a 

 severe infestation of the larva of this species in the Peak District of 

 Derbj^shire. As the enquiry was conducted on behalf of the Board of 

 Agriculture, a full report thereon will be published elsewhere, but certain 

 features in the biology of the insect appear to merit separate reference. 

 The points which have specially come under my notice are as follows : — 



(1) Oviposition. — During August 1916, I observed several females 

 of this species on the moors above the village of Rowarth, near Marple. 

 They were flying in the late afternoon among upland grasses, and their 

 motion was slow and hovering, often remaining in the air but a few 

 inches from the ground among the grass stems. On further investi- 

 gation, it could be clearly seen tlmt they were engaged in oviposition. 

 Their hovering flight was so slow in these instances that, on three occa- 

 sions, I was able to distinctly observe the egg in the act of falling from 

 the body of the female moth into the grass beneath. The spots were 

 easily located, and the egg on each occasion readily discovered, low down 

 among the grass, near the roots of the latter. According to Miss Ormerod 

 (Rept. on Injurious Ins. 1885, j). 13), it is stated that "the eggs are laid 

 in little heaps in the ground." 1 have, however, been unable to trace 

 the original source of this statement, and it is certainly contrary to my 

 own experience, as I have only found the eggs scattered singly among 

 the grass. 



(2) Iliho-nation. — Does Charaeas graminis hibernate in the larval 

 or the egg stage ? According to Ritzema Bos (quoted by Miss Ormerod, 

 Report for 1895, p. 14), the eggs hatch in about three weeks after being 

 laid, and it is a well-known fact that the insect winters in the larval 

 stage! Kollar ('Insects Injurious to Gardeners, Farmers, etc' ; Engl, 

 transl. p. 137) also mentions that the winter is passed in the larval 

 condition. Taschenburg, in his ' Praktische Insektenkunde,' states that 

 the larvae moult twice before finally undergoing hibernation. Reh (in 

 Sorauer's * Handbuch der Pflanzenkrankheiten,' vol. iii, 1913, p. 369) 

 says that the eggs hatch in about three weeks, and the young lai-vae pass 

 the winter in the earth. Siebke ('Enumeratio Insectorum Norvegi- 

 00 rum : Lepidoptera,' p. 53) remarks : " Larva in graminibus, pratos 

 interdum valde vastans, sublapidibus semiadulta hibernat." Finally, 

 R. Service, who has had considerable experience of this insect in 

 S. Scotland, states (Entom. 1894, pp. 279-280) that in a lot of eight 

 snoAV-buntings, shot one January, he found an average of eight or nine 



