﻿50 



BULLETIN 1369, U. S. DEPARTMENT OF AGEICULTUKE 



is not clear that the larvge enter or leave the sjuUet tissue at the 

 paunch end. It is possible that some of them reach the connective 

 tissue by penetrating the muscle along the sides of the gullet. The 

 writers' observations indicate that there is considerable variation 

 in the size of the larvae at the time they reach the gullet, and that 

 the larvge continue to reach the gullet over a much longer period 

 than is covered by the entrance of the larvse into the host. 



Table 4. — Number, size, and direction of travel of larvce of Hypoderma lineatuin 

 in each of 10 divisions of gullets of cattle examined during each month in 

 New York State. 



Month 



Number of larvae headed toward pharynx 

 and paunch in each of 10 divisions of 

 the gullet from pharynx to paunch: 



First pharynx 



First paunch 



Second pharynx 



Second paunch 



Third pharynx 



Third paunch 



Fourth pharynx 



Fourth paunch 



Fifth pharynx. ._ 



Fifth paunch 



Sixth pharynx. _ 



Sixth paunch 



Seventh pharynx 



Seventh paunch 



Eighth pharynx 



Eighth paunch 



Ninth pharynx 



Ninth paunch 



Tenth pharynx 



Tenth paunch 



Total number of larvae headed toward — 



Pharynx _ 



Paunch 



Doubtful 



Grand total _ 



Length of larvae (millimeters) : 



Minimum _.. 



Maximum 



Average 



Number of gullets examined . _ 



Average number of larvae per gullet. 



161 



61 133 



42 203 



l| 



IO4I 336 



3.5 3.0 3.0 4.0 

 4.0 6.0 7. 31 8.0 

 3. 82 4. 62 5. 52| 6. 08 

 61 68| 28 25 

 .112.37,3.71,13.44 



5.0 7.3 



5. oai. 1 



5. 5,8. 69 



15 21 



. 07 1. 57 



164 



6.5 

 14.7 



2' 

 6.07 



118 



8.7 



14.9 



12.13 



72 



1.64 



10.0 



15.6 



13.65 



16 

 11 

 15 

 9 

 27 

 26 

 33 

 35 

 40 

 60 



0.T 



54 

 71 

 76 

 87 

 104 

 73 

 102 



440 



486 



25 



15 440 

 0,2. 16 



Table 4 presents some of the data obtained during the examina- 

 tion of gullets in several localities in New York. Most of them 

 were taken from cattle kept in the vicinity of Ithaca, Chester, 

 Albany, and Buffalo. The combining of the records obtained in 

 several different localities makes the figures more irregular than 

 those obtained at Dallas. The figures show that about 77 per cent 

 of the larva; were found in the posterior half of the gullet. It will 

 be noted that there is considerable irregularity in the average 

 number of larvae per gullet, there being a marked decline in the 

 number in November and December, where it seems almost cer- 

 tain from analogy that the maximum should have occurred. The 

 low average in these two months can be explained by the fact that 

 the gullets were taken from a very few lots and were probably 

 from a very small number of herds of cattle. It is well known 

 that the extent of infestation varies in different herds. 



