Anopheles Propagation Areas 69 



wind direction is uniform and continuous, larvae 

 will be absent on the shore affected by wave action. 

 However, if there are small inlets along the shore 

 line the wave action may not affect the larvae 

 in them, and they will need attention. 



NON-PRODUCTIVE ANOPHELES PROPAGATION AREAS 



In the Cuban anti-malaria campaign as well as 

 on the Isthmus, there were so many apparently 

 suitable places for mosquito development in 

 which the larvae were absent, that attempts were 

 made to determine why Anopheles did not oviposit 

 in them. The attempts were not successful. 

 Larvffi were placed in many of these places and be- 

 came fully developed. Mosquitoes were some- 

 times induced to lay their eggs in non-productive 

 places by putting dead grass there. Investigation 

 and research along this line is essential. Probably 

 new facts will be discovered that may enable us to 

 make existing production areas unattractive as 

 breeding places and render them sterile. A dark 

 brown or reddish substance resembling iron rust 

 (name unknown), which is often accompanied by a 

 small amount of natural oil, is found occasionally 

 on the Isthmus at the edges of ditches or ponds in 

 the form of a limited seepage outcrop and appears 

 to be repulsive to Anopheles. Larvae are never 



