ORDER THYSANOPTERA. 445 



Sp. 2. Thr. L. denticornis. Mas et Fem. Antennae arti- 

 culo 3 ti . extrosum acuminato. 



Fore legs incrassate. The tip of the abdomen in the female has 

 several spines, besides the stronger pair on the back of the last 

 segment. 



On heath and grass ; but rare. 



Sp. 3. Thr. L. cerealium. Mas et Fem. Antennae arti- 

 culo 3 ti0 . rotundato. 



a Thrips physapus. Kirby. Linn. Trans. III. 242. 



Vassalli-Eandi. Mem. Acad. Turin. 



XVI. LXXVI. 



The larva is yellow ; the pupa paler, with long wing cases. 



Exceedingly common on grass and cerealia. Mr. Kirby 

 found them in the furrow of the grains of wheat. Earlier in 

 the year Mr. Vassalli-Eandi detected them gnawing (as he ex- 

 presses it, rather incorrectly, I think) the stems above the knots, 

 and causing the abortion of the ear. It is at this period that 

 their attacks are most mischievous. In the year 1805, one- 

 third of the wheat crop, in the richest plains of Piedmont, is 

 said to have been destroyed by this seemingly insignificant 

 little insect. Whatever the causes may be which produce the 

 alarming increase of these tribes, they appear to operate almost 

 periodically, and over a wide space; for in the same year (1805) 

 the wheat crops in England also suffered from a similar disease, 

 as the communications in contemporary periodicals inform us. 



Mr. Kirby was the first who observed that the male of this 

 species is apterous. 



I have found, within the stem-clasping leaves of Elymus 

 arcuarius, some very small individuals, which may perhaps 

 prove a distinct species. 



Subgen. III. — Aptinothrips. 



Prothorax aequilatns : ocelli nulli nee aloe : antennae articu- 

 lus 6 tus . apice attenuatus, absque stylo articulato. 



Thrips spp. Gleichen (Gmelin.) 



" Linnaeus says of Thr. physapus, "haec forte — unde Secalis spica? exinaniunt:" 

 the "perhaps" has disappeared in Gmelin's compilation. 



