DISTRIBUTION AND ECOLOGY OP CARIBBEAN ANOPHELINES 
101 
but that the distance is covered in a series 
of short flights, during which the mosqui¬ 
toes feed on gametocyte carriers outside of 
the sanitated areas, causing many of the 
mosquitoes to become infected with malaria, 
thus carrying the disease to inhabitants of 
the sanitated areas. According to Le Prince 
and Orenstein (1916), who observed flights 
of large numbers of A. albimanus and A. 
aquasalis in the Canal Zone, the mosquitoes 
become active during twilight; in the even¬ 
ing they flew from a brackish water area to 
Gatun, and in the early morning they re¬ 
turned to the breeding places. These mos¬ 
quitoes flew from a half mile to a mile at 
right angles to the strong dry season winds, 
above ground that had very little protection 
in the form of bush or grass. Judging from 
the actions of birds feeding on the flying 
insects, flight took place from less than six 
feet to 30 or 40 feet above the surface of the 
ground. Jobbins (1940) in Panama also 
observed flight of A. albimanus between 
6: 30 and 7: 30 p.m. Apparently copula¬ 
tion takes place only during twilight hours 
(Rozeboom 1936). 
The seasonal abundance of A. albimanus 
seems to be directly related to rainfall. 
Gabaldon (1939a) shows this in his Vene¬ 
zuelan records. Nevertheless, in some areas 
where breeding is largely confined to im¬ 
pounded waters or rivers, the dry season 
favors the appearance of certain types of 
aquatic vegetation in which breeding is 
especially heavy. This is the case in Gatun 
Lake in the Canal Zone (Curry 1934), and 
in the Chagres River, where Jobbins (1940) 
and Clark, Komp and Jobbins (1940) noted 
the peak of emergence in 1939 to be in 
April, several weeks before the onset of the 
rainy season. In Mexico there is a marked 
reduction of A. albimanus during the dry 
winter season, and in some areas the larvae 
disappear, while the females pass through 
the winter in a state of inactivity (Hoff¬ 
mann 1938a). Giaquinto Mira (1936) 
noted that during the long dry season at 
Champerico, Guatemala, the females re¬ 
mained in crab holes containing water and 
did not mature their eggs until the coming 
of the rainy season. 
The females feed readily on man, but also 
attack animals; in fact, the observations of 
Earle and Howard (1936) in Puerto Rico 
indicate a marked preference by A. albi¬ 
manus for horses and oxen, and while goats 
and pigs were not so attractive as horses 
and oxen, the mosquitoes fed on them as 
readily as they did on man. Le Prince and 
Orenstein (1916) noticed that a horse was 
more attractive than men. In the villages 
of Las Guacas and Santa Rosa, in Panama, 
Rozeboom (1938a) caught 578 Anopheles in 
native huts, of which 472 were A. albi¬ 
manus, but of 349 female anophelines taken 
while they were feeding on pigs near these 
villages, only four were A. albimanus. 
The females are very domestic, and 
within most of its range A. albimanus is the 
most common anopheline found in houses. 
But the females do not remain long in 
houses; most of them return to the jungle 
or to their breeding places, soon after feed¬ 
ing or early in the morning (Barber and 
Komp 1927; Green 1922). They do not 
seem to congregate in preferred daytime 
resting places (Earle and Howard 1936; 
Rozeboom 1938a), although Le Prince and 
Orenstein (1916) saw large numbers on the 
leeward side of trees near extensive breed¬ 
ing places. 
A. triannulatus was described by Neiva 
and Pinto (1922); unfortunately this mis¬ 
leading name has priority over A. bach- 
manni Petrocehi, 1925 (Galvao and Bar- 
retto 1938). The species was described 
from Brazil, but it has been collected as far 
north as Puntarenas, Costa Rica (Kumm, 
Komp and Ruiz 1940). In Panama the 
larvae are found within the cup-shaded 
enclosure formed by the crown of leaves of 
Pistia (water-lettuce), and where extensive 
areas of these plants exist, triannulatus may 
be very abundant. In other countries, the 
larvae may breed among other aquatic 
plants; even in Panama they are often 
found among the floating stems of Jussiaea 
natans (Curry 1931b; Rozeboom 1935). 
Adults of triannulatus have been observed 
attacking man outdoors (Rozeboom 1935), 
but they do not seem to enter human dwell¬ 
ings readily, even in the immediate vicinity 
