genus Acentropus. 275 



rudimentary wings, but slie died without having laid any 

 eggs. 



Here the author's record ends ; for the paper (dated, as 

 already mentioned, in December, 1875) tells us nothing 

 of his observations in 1876 or 1877. And the result 

 seems to be, that out of thirty-seven females from the 

 Kolkje in 1875, some captured and some bred, but all 

 from the same pond, nineteen had rudimentary wings, and 

 eighteen were fully winged. 



The mode of life and the different states are described 

 on pp. 93—105 of the Tijdschrift. 



The oval yellowish-green eggs are laid under Avater, in 

 regular contiguous rows, on the under side of the leaves of 

 Potamogeton. In a fortnight, or thereabouts, the young 

 larvEe emerge, and soon begin to feed. Kitsema says 

 (p. 95), that "in the covirse of a few days some of the 

 larvaa bore into the stalk, or the mid-rib of the leaves, and 

 therein gnaw passages. At what period of their existence 

 they abandon these passages I cannot exactly say, but it is 

 only in their youth that they remain therein." The greater 

 part of the larva3 remain upon the leaves, bend the upper 

 end thereof down, or bite a more or less semi-circular 

 piece out of the edge, spin it fast on the disc of the leaf, 

 and bestow themselves in the habitation thus formed, feed- 

 ing on the leaf that falls within their reach. Later on, 

 the larva forms a dwelling by spinning together two leaves, 

 usually at the ui^per end along the edges. The larvte 

 never leave the water voluntarily. When young they 

 grow very slowly, afterwards more quickly but unequally, 

 so that they gradually begin to differ remarkably in size. 

 After about six weeks some attain their full size, and spin 

 up. The cocoon is placed below the surface of the Avater, 

 against or partly on the stem of the plant, usually in the 

 axils, but sometimes on the under side of a leaf; it is 

 white and stiff, covered on the outside with pieces of leaf, 

 or by the leaf in the axil of which it rests. 



The pupa is of a clear brown colour, darker on the 

 upper than the under side, having three pairs of protube- 

 rant conical stigmata or spiracles, a pair on each of the 

 2nd, 3rd, and 4th abdominal segments. The female pu]ia 

 is distinguishable from the male pupa by its stouter build, 

 and by a slight difference in the knobs or hooks on the 

 under side of the anal segments, and is furnished with 

 full-sized wing-cases in both the forms of female ; but in 



TRANS. ENT. SOC. 1878. — PART IV. (dEC.) X 



