140 



THE SHEEP-TICK. 



nal bristle, and situated in a depression near the mouth. 

 This is a tubular proboscis, protected on the outside by two 

 flat and elongated bristly pieces, the labrum. The organs 



Fig. tJl. — Head ol sheep-tick. Ori.sjinal. Below uterus-like en- 

 largement ot oviduct. Greatly enlarged. After Leuckart. 



used in piercing the skin and in drawing blood are three long 

 and slender bristles of equal length but unequal size, which 

 are withdrawn when not in use. A glance at the illustration 



of a head of the sheep-tick, (fig. 121), 

 will explain this peculiar structure 

 better than words. The abdomen 

 is flat and bag-like. The whole in- 

 sect is densely clothed with hair 

 and bristles; the sexes resemble each 

 other , the male being simply smaller . 



The life-histories of these para- 

 sites are very abnormal, as they 

 bring forth full-grown larvfe, which 

 soon change to pupae without first 

 taking food outside of the mother. 

 Theinsect, instead of depositing an eggupon suitable food, as 

 nearly all other insects are in the habit of doing, retains the 

 same inside an uterus-like enlargement of the oviduct, (shown 

 below head in fig. 121), where it is hatched. Here it is 



Fig. 122. — Young larva and 

 puparium, ^vith breathing- 

 pores, of sheep-tiok. Greatly 

 enlarged. Original. 



