158 AGRICULTURAL EXPERIMENT STATION. 



proved against maculipennis only. In the regions where puncti- 

 pennis is most plentiful the disease is practically unknown, and 

 while within the range of crucians malaria does occur, it is by 

 no means prevalent and niaculipennis is also found there. As the 

 species resemble each other in general habits one account will 

 serve for all. 



Habits of the Adults. 



As compared with the Culex the species of Anopheles are dis- 

 tinguished when at rest by holding the body at nearly right angles 

 to the surface upon which they find a place, the beak nearly touch- 

 ing it almost midway between the anterior and middle legs. In 

 Culex the body when at rest is held parallel with the surface and 

 the beak is directed forward or obliquely downward in front of 

 the anterior legs. 



All the species bite, and bite hard ; the intense pain of the punc- 

 ture lasting longer than in the case of most species of Culex. 

 So also the swelling is usually greater, though this varies with 

 the individual as in all other species. All the species sing, but 

 they can scarcely be said to be deliberate in attack. Yet crucians 

 is the readiest biter of them all and violates tradition by biting 

 during the day. This is a matter of very great importance, 

 because it has been heretofore believed that if the individual 

 retired at dusk into a mosquito proof shelter and remained until 

 after sunrise, there would be practical exemption from danger. 

 The Italian experiments are all based upon this supposed habit 

 of the malaria carriers. i\s to A. niaculipennis I have no reason 

 to doubt the correctness of the belief; as to punctipennis there 

 are exceptions and I have seen the species in the afternoon on 

 porches, but rarely ; as to crucians, that bites readily from sunrise 

 until 1 1 a. m. and from 3 p. m. until and after dark. It is more 

 than probable that it will bite at any time during the day, given 

 a victim in a cool and sheltered location. Were this species a 

 carrier of the disease, there would be no escaping it except 

 under purely artificial conditions. It is a fact, however, that 

 Anopheles do not usually begin to fly or to seek food until dusk. 

 As to the distances for which they fly there are no reliable obser- 

 vations or experiments that enable me to fix a limit. I have 

 reason to believe that they may fly a mile or more, but equal 

 reason to believe that they do not do so habitually. ■ The local 

 limitation of malaria epidemics to points close to breeding places 

 and the practical exemption of large districts of even small towns 

 in which the disease occurs annually, all point to the fact that 

 the insect carriers remain, by preference close to their place of 



