242 
Psyche 
[September 
18. Scale of comb with broad apex, 4-7 stout spines 
communis 
Scale of comb with single stout spine impiger 
19. Both pairs of dorsal head hairs multiple 20 
Both pairs of dorsal head hairs not multiple 21 
20. Anal gills budlike cantator 
Anal gills well developed canadensis 
21. Lower head hairs double — upper 3 hirsuteron 
Upper double — lower single stimulans 
The following genera are each represented by a single 
species : Mansonia perturbans, Uranotaenia sapphirina, 
Psorophora ciliata, Wyeomyia smithii. 
A large part of the study was restricted to the habits 
and biology of A. sollicitans. The eggs of this species are 
distributed over the salt marshes and during the summer 
months hatch when flooded by the waters of the tides and 
rains. The larvae appear soon after the marshes are 
flooded and under favorable conditions develop in 7 to 12 
days. Usually only the larvae in the pools left by the peak 
tides (those most distant from the ocean, within 100 to 
200 yards of the mainland) 4 successfully complete their 
development since these pools are free from larva- 
eating fish and are not flushed by the succeeding lower 
tides. In a particularly dry season the water in many 
of the smaller pools along the edge of the marsh evaporates 
before the larvae complete their development, thereby ef- 
fecting a natural means of control. Pools formed by 
heavy rainfall are usually small and dry out rapidly and 
the larvae are destroyed. 
4 This observation based on conditions existing along the North 
Shore, Massachusetts, in 1930. 
