﻿UNITED STATES DEPARTMENT OF 



DEPARTMENT BULLETIN No. 



Washington, D. C. 



V 



April, 1926 



THE CATTLE GRUBS OR OX WARBLES, THEIR BIOLOGIES 

 AND SUGGESTIONS FOR CONTROL 



By F. C. BiSHOPP, Entomologist, E. W. Laake, Associate Entomologist, and 

 H. M. Bkundrett, Assistant Entomologist, and R. W. Wells/ Entomologist, 

 Investigations of Insects Affecting the Health of Animals, Bureau of Ento- 

 mology 



CONTENTS 



Page 



Bistory 2 



Life history in brief 6 



Disti-ibution 6 



Economic importance 11 



Injury to man 17 



Common names and popular ideas 19 



Hosts 20 



Actions of cattle when attacked by 



adult Hypoderma 24 



Description of stages 26 



How the larvae of Hypoderma line- 



atiim gain entrance to the host 33 



Page 



Development and habits 41 



Seasonal history : 74 



Natural control 79 



A.rtiflcial control 85 



Possibilities of eradication by sys- 

 tematic destruction of grubs 108 



Legislation on grub control 110 



Summary 110 



Literature cited 114 



The cattle grubs {Hypoderma lineatum De Villers and H. hovis 

 De Geer -) are among the most widespread and injurious insects with, 

 which our livestock are beset. Nearly everj^ owner of cattle is 

 familiar with these larvse, which are found under the skin on the 

 backs of cattle in the early spring. Few, however, connect them 

 with the adult insects which are Imown as heel flies or warble flies. 

 Still fewer people have ever seen a heel fly, and many stockmen say, 

 " I have heard all of my life of the heel fly and have seen the cattle 

 run from it but I have never seen one." This has led many to regard 

 the fly with something akin to superstition or to consider its exist- 

 ence a myth. 



Among scientific Avorkei-s there is also a very meager knowledge 

 of the true life history or importance of these insects. Although a 

 considerable nmribei- of veter-inarians, zoologists, and entomologists 

 have made observations and published articles, much of this work 

 has been of a fragmentary character and most of the important bio- 

 logical facts have been establisJKMl during the last decade. It is the 

 writers' desire to set forth briefly the knowledge gleaned to date, and 

 especially to present facts yet unpublished regarding the life his- 



' R<-signed July 24, 

 58252"— 26 1 



1923. 



'Order Diptera, family Ocstrldae 



