TRÄGÅRDH, TILL KÄNNEDOMEN OM DIPTERLARVERNA, 2. 15 



In the 1st instar (Fig. 2) the anterior pair is only repre- 

 sented by a pair of small hairs. 



The spirades (Figs 9 a and b). The 1st instar is 

 metapneustic. In the 2nd the anterior spirades ha ve 17, 

 in the 3rd one 24 »buttons». 



Shape of the hind end. This is characterized by 

 the arrangement and size of the small, conical appendages, 

 which surround the somewhat excavated circumstigmal area. 

 They are placed, one pair dorsally, two laterally and three 

 pairs ventrally. The distance between the dorsal ones is as 

 long as that between the lateral ventral pair. The median 

 ventral pair is placed so closely together that it appears to 

 be one bifurcated tubercle. Through these characteristics 

 the lar va is easily distinguished from that of A. radicum a. o. 



Biology. 



The eggs were found at mid-summer time. When they 

 hatch the larvse use the eggshell as a cover, but soon form 

 a thin oblong, oval tube; the material used is probably either 

 fsecal matter or particles of the fungus cemented together. 

 The former supposition seems the most likely as no fseces 

 were found in the tube. From this cover the lar va makes 

 excursions in all directions on the fungous pasture and de- 

 vorres it, leaving broad, winding streets (Fig. 4, Pl. I). During 

 its growth the tube constantly increases in size, until it be- 

 comes as wide as the grass itself; at the same time the greater 

 part of the fungus disappeares (Fig. 5, PL I). At last the 

 larva attacks the grass itself. 



