A year's work among the gall-gnats. 311 



Thanaos tages, not very common; occurred several times 

 close to the village of Pontresina. 



Hesperia lineola, a few specimens were caught in the Bevers 

 Valley. H. comma, abundant in the Roseg Valley, and many 

 other places. 



Lewes, October 22, 1885. 



A YEAR'S WORK AMONG THE GALL-GNATS (1885). 

 By Petek Inchbald, F.L.S., F.E.S. 



I HAVE succeeded in reading a portion of the life-history of 

 some few gall-gnats during 1885. Some species I have reared 

 only sparingly, others abundantly. 



The first gall-gnat to appear under the bell-glass was 

 Cecidomyia acrophylla (Winnertz), which emerged from its 

 cocoon on the 13th of May, and the gnats continued each 

 morning to put in an appearance till nearly the close 

 of the month. The larva of this gall-gnat affects the 

 leaves of the common ash, causing sausage-like swellings 

 to appear on the under side of the midrib of the upper 

 leaflets. Each gall appears longitudinally on the rib, and 

 contains from three to four tenants. When the larva is full-fed, 

 which is in September, or early in October, the gall splits open 

 on the upper surface of the leaf, and the tenant drops to the 

 ground, and burrows into the soil. I reared the imagines in 

 fair abundance, both male and female, from last year's affected 

 leaves. Kaltenbach raised the gnat in 1874, in May and the 

 early part of June. 



C. cratcegi (Winnertz) was my next hatch. It first appeared 

 oh the 2nd of June, and the gnats continued to appear till 

 the end of the month. The metamorphosis is chiefly external, 

 although occasionally, as Kaltenbach remarks, internal. The 

 larva is instrumental in forming those terminal leaf-rosettes we 

 notice on the shoots of quickset hedges. These contain several 

 larvfe. The leaves of the rosette are curiously contorted and 

 thickened, and thus made to furnish food and shelter to the 

 reddish-coloured larva, which feeds within the leafy tuft. I bred 

 the gnats, as I said, in considerable quantities, during the whole 

 of the month of June. The bosses I gathered in July of 1884, 



