April, '12] JENNINGS: MOSQUITO CONTROL IN TROPICS 133 



genus but its persistence in biting and in gaining entrance to habita- 

 tions are greater than is the case with any other species. In addition 

 to this, it has been shown that upon ingestion of the parasites of mala- 

 ria, a larger percentage of the females became infective and able to trans- 

 mit the disease than occurs with any other species of the region. The 

 breeding places of this species show great diversity of character, though 

 preference is shown by the mosquito for stagnant, fairly pure water, 

 exposed to direct sunlight, with a growth of Spirogyra, which alga is a 

 favorite food. Sewage contamination is inimical to the species when 

 such contamination is marked. Rapidly flowing water also is unsuit- 

 able and streams with a strong current are usually quite free, except 

 in ])ack waters and hollows where the current is little felt. I have 

 never taken albimanus in artificial containers except in one or two 

 instances when the occurrence was evidently purely accidental. With 

 the exception of foul or swift water they may occur in almost any 

 collection of water, however small or seemingly unsuited to mosquito 

 propagation. Hoof-prints, wheel-ruts, the smallest puddle or thinnest 

 film of water seeping upon the ground from a wet hillside, particularly 

 if the ubiquitous algse are present, are points of danger and must be 

 included in the control work. For an Anopheles the flight of albimanus 

 is strong and observations, which unfortunately fall short of demon- 

 stration, indicate that, under a proper combination of circumstances, it 

 will cover a distance of at least one mile from its breeding place. 

 While not domestic in the same sense as Stegomyia calopus, Anopheles 

 albimanus is closely associated with man and finds its most congenial 

 surroundings about his habitations and in the conditions he creates in 

 the course of agricultural, engineering and other work. This fact is 

 correlated with the highly developed blood-sucking habit and has been 

 an active factor in its development and in establishing the economic 

 importance of the species. 



Anopheles tarsimaculata is much less abundant and widely diffused 

 on the Isthmus than albimanus and, though it is exceedingly numerous 

 in certain localities, it is largely confined to the Atlantic seaboard. 

 I have observed but few individuals of the species more than six miles 

 inland, that is, away from conditions obtaining upon the low coastal 

 plain. Where it occurs abundantly it is as great a pest as albitnanus, 

 which occurs coincidentally with it in the neighborhood of Colon and 

 Gatun. It also is a transmitter of the malarial parasite and the habits 

 of the two species are similar. 



Anopheles argyritarsis is less abundant than either of the foregoing. 

 It is known to transmit malaria, at least occasionally. It is widely 

 distributed over the Isthmus but its numbers are never very great in 

 any locality and it is not very frequently found in buildings. By 



