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BULLETIN 1369, IJ. S. DEPAETMEISTT OP AGEiCULTUEE 



the shoulders, that is, above the scapulas or behind the hip bones, 

 the percentage occurring in these regions is comparatively small, 

 the writers figures indicating slightly less than 1 per cent for the 

 latter. Occasionally grubs are met with on the tail 3 or 4 inches 

 below its base, and also on the neck some inches in front of the 

 shoulders. One instance of the occurrence of a grub below the 

 point of the pin bone has been observed by the writers. Laterally 

 most of the grubs are confined to a strip about 1 foot on each side 

 of the backbone in grown animals, but it is not especially unusual 

 to find them on the ribs half way down the side of the animal. The 

 midline of the back is comparatively free (fig. 30). 



The writers' experiments show that there is no relation between 

 the distribution of the eggs on the host and that of the late stages 



Fig. 30. 



-Cow with back infested witli cattle grubs, 

 holes 



Hair is clipped from around 



of the larv£e resulting therefrom. As the larvse are known to 

 migrate freely all through the host, such a relationship would not 

 be expected. 



PUPATION AND DURATION OF THE PUPAL STAGE OF HYPODERMA LINEATUM 



When the larvae have freed themselves from the hole in the skin 

 in the back of the host they begin contracting and expanding and 

 soon roll off on the ground. For the collection of larvae as they 

 emerged from the hosts, burlap bands were placed around the bodies 

 of cattle, as shown in Figure 31. They are not very active and their 

 progress in crawling is very slow. There is a tendency for the larvae 

 to crawl under any loose objects which may be at hand and which 

 would offer some protection; but ordinarily they do not go more 

 than a short distance from the place where they drop, and their 



