PEEFACE. 



THE present work gives a systematic and biological 

 description of the species of the Hymenopterous 

 Families Tenth red hi id ce y Siricidce, and Cynipidce, known 

 at present to inhabit Britain. So far as the two first 

 families are concerned, this is not the first work on 

 the British species; for in 1835, in the seventh volume 

 of his * Illustrations of British Entomology," James 

 Francis Stephens described the species known by him 

 to inhabit these isles. Stephens' work is now obsolete, 

 while since its publication until within the last decade 

 the plant-feeding Hymenoptera have been altogether 

 neglected. This is a somewhat curious circumstance, 

 considering that they are the easiest of all Hymenoptera 

 to name, that many of them possess elegant and beau- 

 tiful forms, and many interesting peculiarities of 

 structure, while their life histories can be worked out 

 with comparative ease, and afford biological and 

 physiological problems of the greatest interest for 

 investigation. The Ciinipidce or gall-flies have been 

 even more neglected, and only a few fragmentary 

 papers have been published on the British species. 





