290 ENTOMOLOGICAL NEWS [Oct., 'l8 



and unscreened. At the beginning of dusk the mosquitoes, 

 attracted by our lights, began mobilizing, and soon they were 

 flying about in veritable swarms, and resting on the window 

 and door screens by the hundreds. Wishing to secure speci- 

 mens for identification, we stepped out on the unscreened fore 

 deck of the boat, and after quickly sweeping a five-inch midget 

 net through the air in a circle a few times, hastily retreated 

 within the protection of the screens. An examination of the 

 contents of the net revealed 39 mosquitoes. All were M. titil- 

 lans. Seven were males and 32 females. In January, 1916, 

 four months later, this house-boat, which was still anchored 

 at the same place, was again visited, but comparatively few 

 mosquitoes came to attack us in the evening. 



A considerable amount of interesting information has been 

 obtained concerning the water lettuce, Pistia stratiotes, which 

 acts as host plant for M. titillans by furnishing the larval and 

 pupal forms with their necessary air-supply. The name Pistia 

 was undoubtedly derived from the Greek word pistos, mean- 

 ing watery, this name being probably gained by the plant's 

 aquatic nature. In many of the Spanish-speaking countries 

 of Central and South America this plant is known as "Sirena." 

 In the West Indies it is commonly referred to as Water Let- 

 tuce, while in other localities it is termed Tropical Duckweed. 

 The appellative of Water Lettuce is quite suitable for this 

 aquatic herb, as it bears a somewhat superficial resemblance 

 to the ordinary lettuce of the garden variety. It is a tropical 

 and subtropical plant and has a wide distribution, being found 

 in many parts of the world. It is distributed in the United 

 States as far north as North Carolina, being especially abun- 

 dant in the St. Johns River in Florida ; throughout Central 

 and South America and the West Indies ; in Africa from Natal 

 to Senegambia and Nubia ; in Asia from the East Indies to the 

 Philippine Islands, and on the Madagascar and Mascarene Is- 

 lands. 



Hogg, 5 in speaking of this plant, says, ". . . . in the West 

 Indies, Africa and India, where it is said to absorb the dele- 



5 Hogg's Vegetable Kingdom. 



