162 MOSQUITOES OF NORTH AMERICA 



(Dyar) has seen a Hydra, accidentally introduced into a breeding- jar, kill a 

 mosquito larva. When Hydra is abundant, as it sometimes is in ditches and 

 small ponds, it may become to some extent a check upon mosquitoes. 



VERMES. 



Martirano has described a minute trematode (Agamodistomum martiranoi 

 Stiles, 1903) found in the body-cavity of Anopheles rnacuKpennis in Italy. 

 Grassi, in his " Studi di uno zoologo sulla malaria" (edit. 1901, p. 197) states 

 that both in the pupa and the imago of Atiopheles a trematode is found encysted, 

 and most likely this is identical with the form observed by Martirano. Since 

 then these " Distomiim " forms have been further studied. They have been most 

 intelligently discussed in a recent paper by Alessandrini, who throws some light 

 on their life-cycle. He believes that these distomi are the larval fomi of 

 Lecitliodendrium ascidia (v. Beneden), a common parasite of the European bat 

 (Pipistrella europcei). The bats are infected by eating mosquitoes which con- 

 tain the Distomum encysted ; the mosquito larvae become infected in turn from 

 the faeces of the bat, containing Distomum eggs, being dropped into the water. 

 The eggs hatch in the water and the larvae of the Distomum enter a mosquito 

 larva and become encysted. These distomi are usually found in cysts on the 

 walls of the stomach or oesophagus of the imago, but sometimes they occur free 

 in the body-cavity. Alessandrini thinks that the Distomum described from 

 Anopheles by Schoo is the same as that of Martirano. On the other hand, he 

 considers a Distomum found in Anopheles by Euge to be the larva of a form 

 (Distomum glohiporum) described much earlier by Linstrow from a snail 

 {Limncea ovata) and which becomes the intestinal parasite of a fish. 



Nematode parasites of mosquitoes were observed in Europe by Stiles as early 

 as 1889 and were at that time already known to Professor Leuckart. However, 

 no record of them appeared until the same or a similar form was discovered in 

 this country, in 1902, by Dr. J. B. Smith. This parasite was described by Dr. 

 Stiles as Agamomermis culicis. In this connection Dr. Stiles discussed the 

 European forms as follows : 



" In the summer of 1889 I collected a number of specimens of Agamomermis 

 sp. from mosquitoes of the species Culex nemoralis taken in the vicinity of 

 Leipzig, Saxony. Whether they were identical with the present form I am un- 

 able to state. The interesting fact may be mentioned, however, that the Leipzig 

 Aga7nomermis was decidedly injurious to the mosquitoes. It was found in the 

 abdominal cavity of larvae, pupae, and adults, so that infection must have taken 

 place in the water, namely, in the larval and pupal stages of the Culex. The 

 infested insects were very sluggish in their movements and could usually be 

 easily recognized as diseased. Many of them died from the effects of the para- 

 site, and the ovaries of infected females were underdeveloped. Professor 

 Leuckart informed me at that time that he had frequently found Culex 

 nemoralis infected with this worm, and that during the years that the worms 

 were most common the mosquitoes seemed to be less numerous." 



Agamomermis was first found by Dr. John B. Smith in the course of his early 

 New Jersey work, while examining the females of Aedes sollicitans, in order to 

 determine the development of the ovaries. He saw a strange enlargement of 



