BIOLOGY AND HABITS OF HORSE FLIES 245 



for the spread of disease, if there are diseased animals in the herd. This 

 habit of bunching up under fly attack applies also to cattle, where the 

 attack is severe. 



I have never succeeded in obtaining any data on the number of blood 

 meals a female will take. Mitzmain states that in the Philippines females 

 of Tabanus striatus bite not oftener than once in 2 days. 



CONCERNING CONTROL MEASURES 



No universal remedy, or control measure, for horse flies can be given, 

 owing to the diverse habits of the different species. In all cases, some 

 knowledge of the life histories and habits of the species involved is 

 necessary before any one can intelligently set in motion control measures, 

 and I may say here that the life histories of very few species of Tabanus 

 are now known. 



In some cases drainage of the larval habitat would undoubtedly be 

 a good control measure. But the degree of drought resistance of the 

 species in question should be ascertained before placing reliance upon 

 this method of control. 



In Russia a species of Tabanus has the habit, in the adult form, of 

 flying to water and dipping the abdomen. Porchinski, the Russian 

 entomologist, advocates the oiling of the surface of the water as a con- 

 trol for this species. It appears that Porchinski has used this method 

 with good results. He applied the equivalent of a half pint of kerosene to 

 six square feet of water surface. If this was not sufficient to do the work, 

 a like amount was used the next morning. It must be borne in mind, 

 however, that not aU species of Tabanus have this dipping habit, and that 

 in order to make the measure effective, the water would have to be com- 

 paratively stiU, as otherwise the oil would soon pass off with the current. 



Occasionally the importation of egg parasites may be an effective 

 control measure. At the present time, Tabanus pimctifer in the Antelope 

 Valley, Mono County, California, is apparently largely controlled by an 

 unidentified hymenopterous egg parasite. 



Hine mentions the fact that in confinement small catfish eat the larvae 

 of Tabanus stygius. It is possible that the stocking with catfish of 

 streams inhabited with Tabanus larvae might have good results. 



In the way of protection of animals from the attacks of adult flies, 

 various devices have been tried, such as nets, hoods, etc. In the Sierra 

 Nevada Mountains, I found in one locality, a very useful horse hood in 

 use to ward off the attack of Tabamis phaenops. This species attacks 

 most viciously about the head and neck of horses. The hood is a simple 

 arrangement made of light canvas to slip over the head and neck, with 

 eye and breathing holes at the proper places. 



