38 BULLETIN 1369, U. S. DEPARTMENT OF AGRICULTURE 
Of the three animals receiving the eggs on the legs, one (No. 417) 
was accidentally killed by a train during the late summer and no 
examination could be made. In November, larve first appeared 
under the skin on the backs of the other two cows (Nos. 167 and 159), 
and during the fall and winter one of them had 8 larve to reach 
the back, while the other had 17. With the animal infested on the 
shoulders (No. 163), a single larva appeared on the back during the 
following winter; but it had been observed that many of the eggs 
on this animal were infertile and had failed to hatch. One of the 
two animals with infestations on the legs and belly (No. 158) was also 
killed by a train and not examined, but the other (No. 22) was 
slaughtered and carefully dissected on July 3. <A total of 40 second- 
stage larvae were found on the viscera and along the gullet. One 
of the two hosts infested by way of the mouth (No. 414) was dis- 
sected on November 26 and no larvee were found in the gullet or 
elsewhere. The other animal (No. 160) was observed carefully and 
repeatedly during the fall and winter and not a single larva came to 
the back. The two animals (Nos. K23 and 92) receiving the second- 
stage larvee through incisions cut near the hock showed 9 and 32 
larvee, respectively. ‘These appeared along the backs during the fall 
and winter. 
During the spring of 1921 two heifers were infested by flies which 
deposited eggs on their hind legs. One of these (No. K23) received 
about 110 eggs on the feet, but apparently none of the 45 eggs 
hatched which were deposited on this animal on March 3. The first 
larva came to the back on October 27, and a total of 64 larve ap- 
peared during the winter. The other heifer (No. 22D) received 
far more eggs on the legs but developed only 8 larve on the back, 
the first appearing November 9. 
During the season seven bovine hosts were infested by placing, 
in pockets cut under the skin, larve of H. lineatwm removed from 
gullets of slaughtered animals. ‘Two of the hosts (Nos. 92 and. 160) 
were infested May 8 with larve (4.5 to 5.5 millimeters in length) 
inserted above the hock. Each developed an infestation in its back 
in the fall. The first larva reached the back October 20 or shortly 
before. Four cattle were infested with 26 gullet larve per animal 
on August 26; two received them in the right hind leg, one behind 
the ear, and one in the back about 8 inches behind the shoulder and 
3 inches from the spinose processes; this was in order to compare 
the dates of appearance of larve on the back and the number suc- 
cessfully reaching that region. 
One of the two hosts infested on the leg (No. 159) had larvae 
present on the back on October 17, and at that time the other animal 
(No. 167-1) was killed and dissected. On a post-mortem examina- 
tion 10 larvee were recovered, 3 in the subdermal connective tissue 
of the back (but no holes had been cut through the hide), 1 under 
the spleen on the paunch, 1 on the paunch near the esophagus, 
3 in the mesentery of the colon, and 2 in the submucous tissue of the 
cullet. One of the latter was near the paunch end of the gullet and 
measured 13.7 millimeters in length; the other was in the middle 
of the gullet and measured 11.6 millimeters. Both were headed 
toward the paunch. 
