212 MOSQUITOES OF NORTH AMERICA 
which had fed well BY. The unfed males were more closely concordant than 
the unfed females, the latter varying over about a semitone. Mr. J. W. Cap- 
stick, M. A., Fellow of Trinity College, Cambridge, to whom we are greatly 
indebted for making these ear determinations for us by means of tuning-forks, 
was not certain that the note given by the males was not one of 440 vibrations. 
Overtones were obviously strong and it sounded at times as if there were a faint 
note of 440 vibrations overshadowed by a strong one of 880. 
“The obvious explanation of the higher note given off by the males is that 
their wings are markedly narrower and shorter than those of the females. Al- 
though a female Culex pipiens gave a higher pitched note than a female A. 
maculipennis, we are not at all sure that it was not simply due to the smaller 
size of the former insect. The male of this species of Culex certainly gave a 
higher pitched note than the female.” 
DISTANCE OF FLIGHT. 
Distances to which malarial mosquitoes will fly is a very important point in 
the consideration of malarial prophylaxis. It seems reasonably sure that they 
are much less capable of extended flight than many other mosquitoes and that 
ordinarily they travel but a very limited distance. Statements that Anopheles 
fly a long distance may be set down as based upon faulty observations. Thus 
Craig has recently stated that he determined a flight of Anopheles of two and a 
half miles in the Philippines. The difficulty of determining, in a tropical region, 
that no breeding-places are present within a radius of two and one-half miles 
must be obvious. When we consider that Anopheles larvee may exist in the 
water-filled foot-prints of animals, and that these may be hidden by vegetation, 
that furthermore they may breed in hollows in trees, or in water-bearing epi- 
phytic plants, the task of determining with absolute certainty the absence of 
breeding-places over a large area will be clearly seen to be impossible. Grassi 
already pointed out that on account of the absence of scaly covering these mos- 
quitoes are less able to withstand desiccation than others and that, therefore, 
they can not cross large areas which afford them no shelter from the direct rays 
of the sun. 
Pressat, who made careful studies at Ismailia in Egypt, objects to the state- 
ment of certain authors that Anopheles fly very long distances and points out 
that they are not capable of sustained flight. He affirms that, when Anopheles 
are present, careful search will reveal breeding-places within a distance of a few 
hundred yards. Pressat admits that under certain conditions Anopheles, pro- 
gressing by stages, travel considerable distances. When they are found at great 
distances from their breeding-grounds they have reached the place in a passive 
manner, transported by wagon, by railway or by boat. They may travel with a 
caravan, as he determined by actual observation at Ismailia, by resting upon the 
animals, the baggage or clothing. Pressat believes that Anopheles can not cross 
a region denuded of vegetation, or a considerable expanse of water. On the other 
hand wooded country affords them the necessary shelter and the animals found 
there furnish them food. 
Celli has concluded, from his observations in Italy, that Anopheles do not fly 
farther than from 200 to 350 meters. When at greater distances from their 
