CONTROL OF HOUSEHOLD INSECTS 



13 



dition for years. This is especially true of Italians. The sequence 

 of events may be briefly summarized as follows : A female mosquito 

 bites a person having malarial 

 germs in his blood. The malarial 

 parasites enter the walls of the 

 mosquito's stomach, undergo cer- 

 tain changes therein, and in from 

 7 to 14 days make their way to 

 the salivary glands and are then 

 ready to enter the system of the 

 next person bitten. These germs 

 then undergo a series of changes, 

 and if the person is not immune a 

 more or less severe case of malaria 

 develops. So far as known, the 

 malarial mosquito, and that only, 

 can carry this infection. The 

 connection between malaria and 

 extensive excavations has long 

 been recognized, though it is only 

 recently that a satisfactory explanation of this condition has [been 

 advanced. Malarial mosquitos breed in large numbers in pools in 

 and about excavations. Italians are our principal excavators. 

 Most of them have suffered from malaria and have the disease germs 



Fig. 3 Malarial mosquito, 1 female, 

 with male antenna at right and wing tip 

 showing venation at left. (After Howard, 

 U. S. Dep't Agric. Div. Ent. Bui. 25. n. s. 

 1900) 



Fig. 4 Common and malanal mosquitos at rest, the latter to the right. (Reduce 

 from Howard, U. S. Dep't Agric. Div. Ent. Bui. 25. n. s. 1900) 



in their systems. The malarial mosquito, breeding in large numbers 

 about recent excavations, derives its infection from the Italians 

 and then, if opportunity allows, inoculates Americans. We 

 therefore frequently have exceptionally severe outbreaks of malaria 



