312 THE ENTOMOLOGIST. 



when the larvae were nearly full-fed. Occasional sprinklings of 

 water, so as to assimilate Nature, are quite essential for rearing 

 these tiny gall-gnats. 



The Cecid of the nettle-gall was the next to appear in the 

 glass-topped box (0. urticce, Perris). It put on wings on the 

 13th of June, and continued to do so for ten days or a fortnight, 

 each morning giving me some three or four. The larva affects 

 the leaf-stalk and ribs of the common nettle, the galls not 

 unfrequently assuming a rosy tint. When fully grown the gall 

 opens, and the larva falls to the ground, pupating in the soil, 

 and spinning for itself a white and silken little web that is 

 readily noticed. The larva of the nettle-gall, I may remark, 

 differs in colour from the ordinary Cecid-larvae. It is whitish 

 during the whole stage of its larval existence. I bred several 

 imagines, both male and female. Like other Cecids, it is very 

 active in its winged state. 



During the closing days of June and the first half of July I 

 bred, in some abundance, from the woolly flower-heads of the 

 milfoil or sneezewort {Achillea ptarmica), the Hormomyia 

 ptarmiccB (Vallot), the H. floricola of Winnertz, and others. I 

 last bred it, by reference to my note-book, in 1861, in August. 

 The affected flower-heads are readily noticed ; for, as Winnertz 

 remarks, " the whole fiower-head is changed into a hairy crown." 

 The pupae of the gall-gnat occupy the central pseudo-florets, 

 whence they emerge in the early morning hours, leaving their 

 silvery shroud behind them in a vertical position. Sometimes, 

 indeed, half the crown is tenanted, sometimes only three or four 

 of the pseudo-florets. You will need to be an early riser to see 

 the transformation scene. I bred fairly abundantly both H. 

 ptarmica and H. millefolii in 1860 and 1861. The one affects 

 the flower-head, the other the axils of the root-leaves, of the 

 respective plants. An urn-shaped gall in the latter case is the 

 result, which contains a single larva that pupates within the 

 gall. The two gall-gnats are, indeed, as distinct in their 

 economy, as in their specific characters. Winnertz, always a 

 most accurate observer, was perfectly aware of their distinctness 

 as species. 



The last Cecid I bred this year is C . persicarice (Linnaeus). A 

 single specimen emerged from its pupa-case on September 3rd. 

 The others I shall not look for till June next. The larvae feed 



