352 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
Culex tar salts; C.fatigans; C.spissipes; C . chrysonotum; C.sitnilis; 
Psorophora jamaicensis; P. texanum; P. signipennis; Mansonia 
spp.: Anopheles crucians; A. punctipennis; A. pseudopunctipennis. 
The most prolific of the above mosquitoes was Culex fatigans, hav¬ 
ing been found breeding from April to December inclusive; while of 
the Anophelinse the commonest was Anopheles pseudopunctipennis, 
which was found breeding throughout the summer months. 
The sluggish Leon Creek, which for more than four miles meandered 
within or in close proximity to the reservation, was at the outset con¬ 
demned as the place from which would come most of the mosquitoes. 
In parts of its course it formed pools more than an acre in area. Its 
course lay through a wide ravine, in places the banks rising fifty feet 
in height; nowhere was it entirely free from a tangled mass of weeds 
and tall grasses, on the whole having the general appearance of a typ¬ 
ical jungle (Plate 6)—an ideal source for the most prolific propagation 
of mosquitoes. To reduce or even eliminate as much as possible 
mosquito breeding in this place through the period of construction, 
resort was made to the use of the oils. The first two attempts were 
local failures. In both cases frames of wire mesh were built to fit 
snugly into a narrow portion of the creek near the place where it first 
enters the reservation. These forms were boarded on the two sides 
which were to be placed against the banks of the creek. The bottom, 
the two sides facing the direction of the stream and the top cover were 
made of wire mesh. This rectangular frame (about 30inches by 36 inches 
by 12 inches) was filled with sawdust which had been soaked in crude oil 
for six hours, and then placed in position in the creek. This proved 
unsatisfactory because of excessive oiling for 24 hours following sub¬ 
mergence, and because its effectiveness was of comparatively short 
duration, and therefore demanded frequent attention. An attempt 
was made to overcome these difficulties by substituting excelsior for the 
sawdust, but with approximately similar results. The third trial, of 
using a large 50 gallon oil drum as a drip, was successful. This drip 
was placed over the channel leading from one of the sewage disposal 
plants into Leon Creek. Two heavy planks stretched across the chan¬ 
nel supported the large oil drum in such a position that the nozzle 
pointed into the middle of the stream. To assure the complete break¬ 
ing up of the oil drops at all times as they fell into the water, two or 
three medium sized rocks were placed in the bottom of the channel just 
in front of the spot where the oil drops hit the water. These rocks 
caused a ripple of sufficient force to break up each drop and at the same 
time to direct the oil to the two sides of the channel. The same pro¬ 
portion of crude and kerosene oils (70 per cent to 30 per cent), which 
was used for general spraying, was found to be satisfactory for use in 
