Genus De^idromyia. 611 



wrigglers embedded in it in all shapes, most in a half coil. The 

 temperature had been down to two degrees below zero. 



These lumps of ice were slowly melted and the larvae gradually 

 freed. They fell to the bottom, rested, and as the ice in the water 

 decreased, gradually became active. 



The larvae were found to feed well, but in spite of being kept 

 warm they developed but slowly. 



They pupated in March, and in three days the adults appeared. 

 In the open the first pupa seen was on April 16th. 



Some of the larvae received by Professor J. B. Smith that 

 must have come from eggs laid in November did not hatch out 

 until September, thus remaining in the larval stage ten months. 



The eggs are mostly laid on the young leaves when still 

 perfectly dry, both at the bottom and sides, singly or in groups. 



The eggs are chestnut brown, bean-shaped, the ends somewhat 

 pointed, and show an irregular tessellated reticulation. 



That the larvae do not need air as Culex we know, because 

 Howard kept them for two weeks under a film of oil. This is 

 because there is a complex tracheal system in the anal processes, 

 which form really a gill structure, so that the insect gets its 

 oxygen direct from the water. i 



Professor J. B. Smith sums up the life-history as follows : 

 "The insect winters in the larval stage, freezing and thawing as 

 often as need be during that season. It pupates late in May, and 

 becomes adult a week or ten days later. Eggs are laid in the 

 leaves, singly or in small groups, fastened to the sides or floating 

 on the surface. The summer broods mature in about a month, 

 and there are three, if not four, series ; but the broods overlap so 

 much that the breeding is practically continuous. Late in the 

 season the adults select the new leaves for oviposition even if 

 they are yet dry." D. W. Coquillett informs Professor J. B. 

 Smith that he has this species from Florida, where it breeds in 

 the leaves of orchidaceous plants growing on trees. 



The larvae vary in length from 5 to 6 mm. ; creamy white in 

 colour with slightly dusky head ; the antennae are short, and 

 have the lateral tuft represented by a single hair only, near the 

 apex ; labial plate broad and narrow, a large apical tooth and 

 from 7-10 on each side; lateral combs of eighth segment consist 

 of 11 to 15 scales arranged in a single row, the scales are rather 

 long and fringed with hairs on each side ; there is no pecten on 

 the siphon, which is, however, provided with numerous long hairs 

 all over its surface. 



2 r 2 



