MICROSPORIDIA — PARASITIC IN MOSQUITOES 179 



of water where fish cannot be introduced, one may use oils for 

 the destruction of those larvae. 



Increasing the chances of Thelohania-infection among mosquito 

 larvae and distributing of the infected larval tissue into the breed- 

 ing place may be another method of destroying mosquito larvae 

 in a small body of water. In case the infection be slight, the 

 larvae, although infected, may become adults, and thus distribu- 

 tion of the parasites will be done by the host mosquitoes which 

 will die on oviposition, leaving a source of infection in places 

 which may escape our watchful eyes. The practical application, 

 however, depends upon further study in future. 



SUMMARY 



1. Three new Microsporidia obtained in the vicinity of Ur- 

 bana, Illinois, U. S. A., are described here. 



2. Thelohania magna infects the adipose tissue of the larva of 

 Culex pipiens. It is rare, and is found in a limited locality. 

 The effect of heavy infection upon the host appears to be fatal. 



3. Thelohania illinoisensis infects the adipose tissue of the larva 

 of Anopheles punctipennis. It is rarer. 



4. Nosema baetis attacks the adipose cells of the nymph of 

 Baetis sp. It is more common than the other two. 



5. Caryogamy or autogamy was not found in the sporogony 

 in any of the three forms. 



6. Two types of microsporidian spores are distinguished. One, 

 represented by Thelohania magna, has a spore in which the sporo- 

 plasm occupies its posterior portion and the polar capsule the 

 anterior part. The other, represented by Nosema bombycis, has 

 a spore in which the sporoplasm surrounds the polar capsule at 

 its middle part. 



7. The hypertrophy of the nucleus of the host cell is observed. 



8. The phagocytosis by the blood-cell of Baetis nymph of the 

 parasites possibly occurs. 



9. The fact that the polar filament cannot be used for the iden- 

 tification of species of Microsporidia is made clear. 



10. The possibility of using microsporidian parasites as one of 

 the means of destroying mosquito larvae is suggested. 



