NOTES ON A NEW DIPTEROUS INSECT BELONGING 

 TO THE FAMILY CECIDOMYIDjE INFESTING 

 GRASS; ALSO ON TWO HYMENOPTEROUS IN- 

 SECTS PARASITIC UPON THE FORMER. 



By Frederick A. A. Skuse. 



At our meeting in May last, Mr. Macleay exhibited some mal- 

 formed grass, which he described as infested with a minute grub, 

 which lived in the stem and caused a thickening of it, and which he 

 suspected to be the grub of a minute dipterous insect, probably 

 belonging to the family Cecidomyidce or gall-gnats. Subsequently 

 Mr. Macleay handed the grass over to me for investigation. When 

 I first saw it T recognised the larvaj and habits of the Cecido- 

 myidce, and I have since carefully watched for the advent of the 

 perfect insect. On December 5th, the first imagines emerged, and 

 they have continued to come out in a very irregular manner up till 

 the present time. Only a small number of the flies have emerged 

 compared with the quantity still remaining in the larval state. 

 This evening I have for exhibition a box of specimens illustrating 

 almost the whole life-history of the insect in question. 



The fly belongs to the genus Lasiojjtera, and although the habits of 

 this species are in some particulars similar to those of the so-called 

 "Hessian-fly" ( Cecidomyia [Dvplosis) destructor), which, has for more 

 than a century proved exceedingly destructive to wheat in America 

 and elsewhere, the two insects are very distinct in appearance and 

 belong to totally diflerent genera. It is not at all likely to attack 

 wheat, or in fact anything but the species of grass upon which it 

 has been discovered, as most of the larviB of the gall-midges live 

 exclusively in a certain species of plant only. Further than this 

 — each species always attacks the same part of a particular plant ; 



