CHAPTER XVI 



TAPEWORMS OF CHICKENS 



Though tapeworms are comparativelj' frequent in chickens and other 

 domestic fowl, they have not up to quite recent times been the subject 

 of anj' considerable investigation in this country. In our hterature upon 

 the parasites in general, if not neglected entirely, but one or two species 

 are as a rule described, and these generall}' in an incomplete manner. 



With the exception of but one species, what is at present known as 

 to the larval forms has been determined from studies upon poultry 

 cestodes in foreign countries. Thus far in these investigations the life 

 C3'cle of but one chicken tapeworm — Davainea proglottina — has been 

 experunentally demonstrated, the only one among the six here described 

 which has not been reported in this country. The remaining five have 

 been found infesting chickens in various parts of the United States. 



1 . Choanotaenia inf undibulif ormis iDrepanidotama injimdi- 

 buUformis) (Fig. 102)— The head (Fig. 103) is small, globular 

 or conical, and bears a crown of 16-20 hooks. The suckers 

 are prominent, may be projecting. The neck is very short. 

 The first segments are short; those following are infundibuli- 

 form, with anterior border narrower than the posterior. The 

 genital pores are irregularly alternate. 



The length varies from 2-23 cm. {%-^\^ inches). 



Grassi and Rovelli, comparing cysticercoids which they had 

 found in flies (Musca domestica) with the adult Choanotcenia 

 inf undihidif ormis, noted a stmctural agreement from which 

 they inferred that the larvae were the intermediate stage of 

 this species. No experiments were carried on by these in- 

 vestigators, however, to demonstrate this connection. 



Guberlet, of Oklahoma Agricultural and Mechanical Col- 

 lege, in a series of investigations upon chicken cestodes (1912- Fig. 102. 

 1914) seems to have conclusively demonstrated that the ^nia^^'Jnl 

 cysticercoid of Choanotcenia infundihidiformis occurs in the fundibuli- 

 common house fly. Briefly stated, his results were obtained formis, — 

 by raising cysticercoids in the flies by feeding them on the 

 eggs of the tapeworm. These flies were fed to three of six chicks 

 which had been removed from chance infection as soon as hatched. 

 Three weeks after such feeding all of the chicks were killed, and two were 

 found to be infested with Choanotcenia infundibuUformis. The three 

 birds used as a check on the experiment contained no worms. 



