174 MOSQUITOES OF NORTH AMERICA 



the fact that the larvae of this mosquito are not green, even when found among 

 vegetation of that color until nearly full grown, after which, like the larvae and 

 pupas of Anopheles quadrimaculatus , they may be bright grass-green. These 

 mites lived for several days on the larvae, but when removed from them and 

 placed in water, they soon sank to the bottom and died. 



" It is possible that the bluish green mite of Culex abominator is a different 

 species, for I have never found them of this color on Anopheles quadrimaculatus; 

 yet under similar circumstances the larvae, pupae and freshly emerged adults of 

 this mosquito are also bright green. It is certainly ver}' probable that this mite 

 destroys quite a good many mosquitoes, and it is unfortunate that they do not 

 extend their operations throughout the season instead of only the early part. 



" A good many species seem to be for the most part never or only very rarely 

 attacked at all," 



In considering the whole question of the effect of these mites it seems doubtful 

 whether they destroy adult mosquitoes. Mr. Banks gives as a result of his ob- 

 servations that mosquitoes that do carry mites do not seem to be inconvenienced 

 by them. The mites, he states, can not live long out of the water, and can never 

 complete their transformations. If extremely numerous their weight might 

 hinder the flight of a mosquito, or they might take enough nourishment from 

 the host to seriously weaken it. Mr. Banks's observations have been made for 

 the most part in the vicinity of Washington, where this mite infestation is rare. 



In their work on malaria in Algeria, the Sergents made a number of observa- 

 tions upon these parasitic mites. They found there that the mites seem to occur 

 only on Anopheles and never upon Culex or any other genus of mosquitoes. 

 Their specimens were examined by Trouessart, who found them to be hexapod 

 larvae of hydrachnids which could not be determined in the larval condition 

 but which probably belonged to the genera Eylais, Hydrodroma, Hydryphantes, 

 or Diplodontus, whose larvae are known to have parasitic habits but whose dis- 

 tinctive characters are too slightly marked to connect them with the adult forms. 

 Parasitized Anopheles were found by them from May to October, in the larval, 

 pupal and adult condition. They found nine larvae, two pups, twelve adult 

 females and five adult males of Anopheles maculipennis so parasitized on the 

 plain of Mitidja and in the valleys of Kabylia. They were able to follow in the 

 laboratory the development of most of the parasitized larvae and these underwent 

 their metamorphoses normally and did not seem to be inconvenienced by the 

 hydrachnids. When the larva transfonned to pupa the hydrachnids passed 

 from the larval skin onto the pupa, and when the adult issued the mites left 

 the nymphal skin and attached themselves to the winged insect. In their ex- 

 perience these parasites are rarely single, and as many as ten were found upon 

 the same insect. With the larvae and adults they were found upon the abdomen ; 

 with the pupffi upon the dorsal portion, near the point Avhere the skin splits to 

 allow the adult to issue. They were attached to the host by their beaks and were 

 observed to grow. The Sergents tried an experiment to see whether the larval 

 hydrachnid can change its host. A female of Anopheles algeriensis was put into 

 the same cage with two specimens of Anopheles maculipennis which carried 

 numerous mites. The next day, upon the abdomen of the Anopheles algeriensis, 

 found dead, they found a mite. From this experiment they concluded that these 



