F. W. Edwards and C. B. Williams 259 



any doubt identical with the Sda/ra trilici described by Coquillet from 

 North America in 1895. 



Coquillet made positive statements as to the injury caused by the 

 larvae to young wheat plants. He says {Insect Life, Vol. vn, 1895, 

 p. 407): "On March 17, 1885 a large number of adults issued from a 

 jar containing plants of this kind that had attained a height of from 

 <> to 8 inches. They already indicated an unhealthy growth by a more 

 or less yellowish appearance, and an examination of their roots revealed 

 the fact that these had been severely injured by the larvae, many of 

 which were still present, and were observed to feed upon the roots 

 and interior of the stems both below the surface of the soil as well 

 as in the interior of the steins a short distance above the surface. As 

 many as eight larvae were sometimes found in one of the stems, and 

 they had also penetrated the kernels of wheat from which the plants 

 sprang; many of the smaller rootlets had also been devoured, or more 

 or less injured, by them." 



Mr St Quintin was equally definite in attributing the damage to 

 the Sciara larvae 1 , as the following extract from his letter will show: 



"It is causing great trouble and loss to raisers of exotic orchids 

 and seems to be on the increase. The books written only a few years 

 back do not allude to it amongst the insect pests which trouble orchids 

 under cultivation. Certainly here, though we have been raising orchids 

 (from seed) for about 8 years, until the last three or four we have 

 never noticed it. It is particularly troublesome this spring, but it- 

 seems to fly all the year round, at any rate whenever we have young 

 orchid plants at a particular stage, we find it in our seedling house. 

 This house is kept very moist, and with a temperature of from 70°-80° F. 

 according as the day is dull or sunny. 



"When the little plants have acquired the real root, the fly does 

 not trouble them, but at the very early stage when the plant draws 

 its nourishment from root-hairs it cuts these off and starves the plant. 

 When it has destroyed all the little plants in a pot it turns to the 

 Sphagnum moss and devours that. 



"Fumigation kills the insect when it is on the wing, but it appears 

 to emerge at all hours of the day, and does not mind the fumigation 

 in the larval and pupal stages. 



"It seems a question whether the fly came with the Osmunda fibre, 



1 Some of these larvae have been handed to Mons. D. Keilin, who will describe 

 them in his forthcoming work on the early stages of the Diptera. 



17—2 



