GALL GNATS. 33S 



flowers of wattles, and galls are formed by the 

 distortion of the pods, making a mass of continuous 

 galls. The well-known '^hessian fly" {Cccidomyia 

 destructor) attacks the stems of wheat, which 

 weakens them and causes them to bend, and so the 

 ''ear" does not mature. 



To observe these tiny flies, get a glass preserving 

 jar and put in some damp sand, and in the latter 

 place some sprigs with galls present. Put a 

 piece of muslin over the top of the jar. By 

 cutting open some of the galls the larvae and pupa?, 

 may be seen. Froggatt thus describes some of the 

 Australian gall gnats: "Diplosis paralis forms curi- 

 ous little blisters upon the young foliage of Euca- 

 lyptus corymbosOf dotting the leaves all over with 

 I'eddish spots with a keyhole-like mark at the apex. 

 Z). eucalypti aborts the young twigs of eucalyptus 

 into gouty swellings, in which a number of larvai 

 feed and pupate. There are certain rounded, shot- 

 like galls of the Eucalyptus, generally several in 

 number and on the midrib of the leaf, which, on 

 account of the pupal skins always remaining in 

 the holes in the side of the galls through which the 

 flies have escaped, can be easily distinguished from 

 very similar ones that are the work of micro- 

 livmeiioptera. " 



