94 NATURAL HISTORY OF AQUATIC INSECTS CH. 



female bites small round or oval holes in the leaves, 

 and through these apparently passes the eggs to the 

 under side, where she arranges them in a single or 

 double circle around each hole. The larvae, when 

 hatched, descend to the bottom, and begin to feed on 

 the roots. They exhibit no obvious adaptations to 

 aquatic life — no swimming organs, no gills, no peculiar 

 shape — but only the dirty-white colour, the semi- 

 cylindrical figure, the small, hard head, and the three 

 pairs of pointed legs, found in an ordinary larva which 

 buries itself in earth. When full grown, they are 

 about half an inch long. Their movements are very 

 sluggish. 



Close examination with a magnifying glass reveals 

 just one peculiar structure. Towards the hinder end 

 of the body, on the 8th segment of the abdomen, there 

 project from the dorsal surface two slender curved 

 spines, and to the bases of these pass the longitudinal 

 air-tubes, which traverse the whole length of the body. 

 There are also two pairs of more flexible set^e, which 

 fringe the last segments. At the roots of the spines 

 are a pair of small openings, which look like spira- 

 cles. 



Roots of Nymphaea frequented by Donacia were 

 observed by Schmidt-Schwedt ^ to exhibit peculiar 

 scars. These were discovered with difficulty, owing 

 to the dark colour and uneven surface of the roots. 

 There was in each case a rough hole, made apparently 

 by the jaws of the larva when feeding, and, at a dis- 

 tance corresponding with the length of the body, a pair 



' Berl. Ento!?i. Zeiis., Bd. XXXI. pp. 325-334, Taf. V. figs. 

 i-ii (1887). 



