INJURIOUS INS.ECTS. 257 



is an important inquiry. It is very probable that the larva can work 

 its way to the surface, from a greater depth than what the pupa can. 

 Direct experiment only can determine accurately at what depth the 

 insect, in both these stages, must be buried in order to destroy it. 

 No information of any value can, therefore, be given upon this point, 

 until such experiments are made. 



Description of the clear-winged wheat-fly. 



The importance of full and accurate descriptions of every one 

 of the several parts of a natural object, in order that it may be iden- 

 tified with certainty, is strikingly illustrated in the present species. 

 For some years it has been supposed to be identical with the Eng- 

 lish wheat-fly ; but those who are aware of the large number of both 

 plants and animals in Europe, that have analogous representatives 

 in this country so closely resembling them as to have been in many 

 instances for a long time considered identical even by accurate and 

 experienced observers, could not but entertain doubts upon this 

 point ; and with the fifteen or twenlv characters of this insect which 

 could be gathered from different sources, I could still only say that 

 our wheat-fly was probably the tritici of Mr. Kirby, some of its 

 prominent peculiarities seeming even to conflict with the descrip- 

 tions given of that species. For instance, all that we could gather 

 respecting the form of the joints of the antennae, was, that they 

 were " moniliforni'' ; and Messrs. Kirby and Spence, in their " In- 

 troduction to Entomology," define this term to mean " oval or glo- 

 bular joints, like a necklace of beads." Now the joints of the an- 

 tennas in our insect are oblong, and each has a marked contraction 

 in its middle, thus approaching to an hourglass shape, a form the 

 very reverse of " oval" or " globular." It was not until I saw the 

 excellent figures and descriptions of Mr. Curtis, that I became well 

 assured that our species was identical with the European. 



The common reader will get the most clear and definite idea of 

 the appearance of the wheat-fly, by being told that it looks almost 

 exactly like the wheat-worm with wings and legs added to it. These 

 members, however, are so very small as to be scarcely recognized 

 by the naked eye, except when they are fixed intently upon the 

 object. 



The HEAD of the female Cecidomyia tritici (Plate 5, fig. 1) is of 

 orbiculate or flattened-globular form, with the eyes forming its 



