520 Mr. C. L. Withycombe's Notes on 



recurrent humeral vein. The costal field is narrow. Sc and Ri 

 coalesce near the a-jiex of tlie Aving. Only one sector leaves the 

 radius. 



Likely to be confused with Sympherobius elegans or 

 incons'picuus, but the venation is quite different. Sisyra 

 terminalis differs from S.fmcata in the tips of the antennae 

 being whitish. 



Sisyra occurs as the imago throughout the summer, but 

 most abundantly in May and June along the banks of 

 rivers and canals, or lakes. It is rather sluggish, and may 

 be beaten from shrubs and trees, especially alders, over- 

 lianging the water. 



Eggs are laid in depressions of leaves, i. e. along the 

 veins, etc., also on wood piles and other objects standing 

 in, or overhanging the water. They are placed in clusters 

 of from one to twelve, often quite irregularly. Over the 

 batch the female then spins a white silk web, very like 

 that of the Psocoptera. The silk strands are drawn across 

 in parallel lines; then changing her position slightly, the 

 female cross-hatches the first strands with another layer at 

 a different angle. Generally there are three or four layers 

 of silk, so that the eggs are barely visible. In Psocids, of 

 course, the eggs can usually be plainly seen through the 

 silk covering. 



Each egg is -35 mm. long, of elongate oval shape and 

 pale yellow colour. In form it resembles the egg of 

 Hemerobius, but the micropylar knob is somewhat more 

 flattened and the chorion is not markedly reticulate. At 

 the end of a week no appreciable change in colour has taken 

 place, but the eyes are visible as reddish spots. These 

 then darken and the head also becomes slightly darker, 

 but until just before hatching the egg is still mainly yellow. 

 In fourteen days at 63° F., eggs hatched. The larva saws 

 a slit in the chorion with its egg-breaker (Plate XXXVIII, 

 fig. 1) and often also cuts through the silk covering of the 

 eggs by the same means. Then the amnion skin is cast, 

 before completely leaving the egg, and the young larva 

 drops on to the water. Bending the tip of the abdomen 

 up to the back of the head, the larva then slowly squirms 

 over and forces itself below the surface film. When sub- 

 merged, the larva floats midway in the water with head, 

 legs, and tip of abdom.en bent under itself ventrally. It 

 will be seen that in the thoracic region the gut contains a 



