 Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in...  Gentleman's Magazine and Historical Review - Page 821883Affichage du livre entier - À propos de ce livre
 | 264 pages
...district. The cause is that a certain fly lays its eggs in the navel of the new-born offspring. He adds, "The increase of these flies, numerous as they are,...habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic... | |
 | 1912 - 538 pages
...and northward in a feral state." This is due to the prevalence in that country of a certain kind of fly which lays its eggs in the navels of these animals when first born, which results in their destruction. Thus cattle, horses, and dogs are among the unfit in one region... | |
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