OBSERVATIONS ON THE DISTRIBUTION OF WARBLE 



FLIES IN OHIO. 



Dox C. Mote. 



The following discussion is based on a study of the numbers, 

 dates of occurrence, and distribution in Ohio of the Ox Warble 

 flies (Hypoderma bovis and Hypoderma lineata) as determined 

 from an examination of 628 grubs and 15 adult flies collected 

 for the most part during the years 1914 and 1916. The general 

 object of the study is to determine (1) whether both species 



FiG.l. Larvae were taken from the backs of different cattle at the positions marked X. 

 The part of the animal in which the grubs are found during their last stages 

 is the back. Here they may be found distributed for the most part from the 

 loin to just back of the shoulder. Less frequently they may be found on the rump, 

 or some distance down on the side or on the shoulder. The choice of the back 

 region to go through the last stages has some advantages. Here they are less 

 likely to be injured; there is less pla}^ of the muscles, and the animal itself is less 

 likely to receive serious injury. 



occur within the state; (2) which of them are numerous enough 

 anywhere and at any time to be notably injurious in the grub 

 stage to dairying and the beef cattle industry; (3) the local 

 and regional distribution of the grubs; and (4) to learn, if 

 possible, ■ what are the conditions favoring the increase or 

 decrease in numbers of the species in the not unreasonable hope 

 that this knowledge may help in the solution of the problem 

 of combatting these parasites. 



Location of Collections. — ^Of the 32 counties throughout 

 the state from which collections were obtained, 10 were in 

 northeastern, 10 in northwestern, 10 in southwestern, and 2 



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