238 Annals Entomological Society of America [Vol. VIII, 
for Thysanoptera, found a male of this species inside of a flower. 
But if the female mosquitos of these species do eat fruit juices 
under natural conditions, it appears only fair to believe some 
one of the able sanitary corp of the Isthmus would have made a 
few observations of the fact. The infrequency of such observa- 
tions is explainable on the presumption that human blood is 
preferred and so soon as a human being is anywhere near, his 
presence is quickly detected and sought long before he could 
have found out the whereabouts and doings of these pests. 
This at least is true of the half dozen common species on the 
Zone. 
Jennings (1912) in his survey of the upper Chagres River 
valley, did not encounter adults of A. albimanus Wiede. nor 
larvee, though habitats were seen which if present on the Zone 
would favor Anopheles breeding. He attributes this absence 
to the absence of habitations, a presumption fairly accurate. 
Buseck and Orenstein made a trip to the Upper Trinidad valley 
near Gatun, and but one albimanus was collected by them, 
though the sylvan Anopheles were abundant. (There is some 
doubt as to the authenticity of this single albimanus as it may 
be an accidental mix-up with mosquitos from the Zone.) The 
writer in his inspections of the Canal Zone, found albimanus 
to breed only near settlements. It therefore seems quite 
plausible to believe that the pathogenic species of Anopheles 
become more and more restricted to human settlements, an 
adaptation which no doubt will hold for all animals which play 
a role similar to that of albtmanus in the transmission of disease. 
This trend is probably due to repeated feedings upon human 
blood, and it may be that the development and establishment 
of the malarial parasite within the mosquito may have had a 
tendency toward such isolation. The restricted distribution 
of Aedes calopus tends to strengthen the idea that pathogenic 
species cling to inhabited regions. 
It also appears that a meal is necessary prior to oviposition. 
The studies of Darling (1912) indicate such to be the case. 
The author (1913-c) recorded a case of oviposition in Aedes 
calopus where prior meal was absent. The fact that the 
mosquitos concerned in the flight to Gatun returned daily to 
the marsh, would indicate that food and oviposition were 
closely linked together. It appears only natural that a mos- 
quito upon emergence from its, pupal prison, should seek, first 
