EXTERNAL PARASITES 



49 



among birds of average value is to kill all the 

 birds in an infested flock. None of them should 

 be sold, as they may find their way into other 

 flocks and infest them. It is a very serious disease 

 and one of which it is difficult to rid the flock. 



Chigger (Jigger) or Red Mite Infestation 



There are two varieties of chiggers found in this 

 country, one is the Trombidium holosericeum, the 

 other the Dermanyssus gallince. 



Fig. 12 Fig. 13 



Fig. 12. Cytodites Nudus 

 A, Rostrum. B, ambulacrum. C, pedicle of am- 

 bulacrum. 

 Fig. 13. Trombidium Holosericeum 

 A, Mouth parts. B, palpi. C, booklets on free ex- 

 tremity of the leg. D, uterus filled with eggs. 

 Drawing to right indicates actual size. 



Trombidium Holosericeum 



This parasite is the common chigger (jigger) or red mite 

 of the henhouse. 



Description. — It is very small, as indicated by the mark 

 by the side of Fig. 13. The body is oval in shape (shape 

 of a hen egg) ; it is provided with four pairs of legs in the 

 adult state and three pairs in the larval. The distal end of 

 each leg is provided with two booklets or claws, with which 

 it clings to objects and which enable it to crawl about. Its 

 mouth parts are conical in shape, as illustrated in the draw- 

 ing. (See Fig. 13.) 



Life History. — Mites lay their eggs in the cracks and 

 crevices and fllth of henhouses. If the temperature is warm 

 the eggs hatch in a few days into the asexual, six-legged state. 

 After passing through a few moults it arrives at the eight- 



