PARASITES THAT ARE FREE WHEN OLD. 



176 



teresting account of one of tliem in the bulletins of the 

 Belgian Academy. 



A gadfly found at Cayenne is distinguished by the 

 name of the Macaco Worm; it belongs to the genus Cute- 

 rebra, and usually attacks the skin of oxen and dogs in 

 South America. It is accidentally found sometimes on 

 man. This is the Cuterebra noxialis. We here give 

 the representation of it. 



There is also a gadfly on 

 the ox. 



Professor Jolyhas devoted 

 himself to zoological re- 

 searches on (Estridse in gen- 

 eral. Professor Schroeder 

 Yander Kolken, in Holland, 

 and Mons. Brauer, in Aus- 

 tria, have studied them with 

 great success. 



The Hippoboscus is a fly 

 which is very greedy of 

 blood, and attaches itself to 

 horses and oxen, especially 

 under the tail, in the parts 

 where there is less hair. It 

 sometimes also attacks man. 



The Hippoboscus lives on the horse, and an allied 

 species, of which a different genus has been formed, lives 

 on bats {Strebla vespertilionis) in South America. Mons. 

 Yon Baer noticed hippobosci on the elan, during his 

 residence in Konigsberg. 



Many other insects live and develop themselves at 

 the expense of their nearest neighbours. 



Fig. 37. — Macaco Worm. 



