10 BULLETIN 939, U. S. DEPARTMENT OF AGRICULTURE. 
SIGNIFICANCE OF TURKEYS IN RELATION TO GAPES FORMERLY 
UNRECOGNIZED. 
From the literature on gapes one may gather further evidence of 
the importance of the turkey as a carrier of gapeworms, though the 
peculiar significance of the turkey in relation to gapes has not been 
recognized by former writers. In the first published record of gapes 
AViesenthal (1799) called attention to the frequent occurrence of the 
disease in Maryland and stated that it was most prevalent among 
young turkeys and chickens bred upon old-established farms. The 
first published record of gapes in England is that of Montagu 
(1811), who notes that it generally attacks chickens at the age of a 
month to 6 weeks, and that it " seems to be peculiar to the young 
of the common domestic fowl, since neither my turkeys nor ducks, 
all of which are reared together upon the same spot, have even been 
attacked." 
Von Pocci (1904), in discussing an outbreak of gapes among 
young pheasants in Bavaria, which killed about 60 per cent of the 
birds, incidentally remarks that turkeys were used as brood hens 
for young pheasants. The first record of gapes in Norway (Home, 
1910) is based upon the discovery of gapeworms in two young 
turkey poults and two young chickens from the same poultry farm. 
How frequently turkeys have been associated with the occurrence 
of gapeworms among chickens, pheasants, and other birds in Europe 
is not indicated in the published reports that have come to the 
writer's attention other than those just mentioned. These, however, 
are very suggestive and, together with the observations recorded in 
the present paper, may be taken as an indication of the probability 
that the turkey has been chiefly, if not entirely, responsible for the 
spread of the gapeworm to various parts of the world. 
TURKEY THE PREFERRED HOST OF THE GAPEWORM. 
It would seem quite probable that the gapeworm, like the turkey, 
was originally limited to America and that it has reached other 
countries only as it has been carried by the turkey, which, because 
of the tolerance it has to infestation with the gapeworm, may be 
looked upon as the natural host of this parasite. 
The fact that the gapeworm in turkeys grows to a larger size than 
it does in chickens may be taken as evidence, in addition to that 
already given, that the turkey as compared with the chicken is the 
preferred host of the parasite. The difference in the size of the 
worms may be a simple correlation with the size of the trachea, but 
it seems more likely that other conditions than the mere size of the 
trachea play a part in bringing about the differences in the size of 
gapeworms in chickens and turkeys. The maximum length of gape- 
