MONTANA INSECT PESTS, 1947 AND 1948 23 



results of such programs have been quite successful. These 

 ranchers report that the incidence of grub infestations has been 

 greatly reduced. 



CATTLE LICE 



The interest shown by ranchers in louse control parallels that 

 shown in cattle grub control, even though cattle louse problems 

 have existed for years in varying degrees and intensity. While the 

 reasons for seasonal variations in intensity of infestations are 

 fairly well established, the variations which occur from year to 

 year remain unexplained. There are three types of cattle lice which 

 have a general distribution over the state. They are the long nose 

 cattle louse {linognathus vitidi), the short nose cattle louse 

 (Haematopinus curysternus), and the biting louse {Bovicola 

 hovis) . With the development of new insecticides which are more 

 effective against lice, it is expected that cattle lice control will 

 soon be an established practice in the livestock industry. An 

 increasing number of growers are now including cattle lice control 

 in their herd management programs with very successful results. 

 The State Entomologist's office is being requested to furnish 

 information on materials and methods for setting up and carrying 

 out these programs. 



HORN FLIES (Haematohia irritans) 



For many years these insects have been pests of livestock 

 over the entire state. Now that effective methods of controlling 

 horn flies have been developed, it has become evident that heavy 

 infestations of these insects have been responsible for preventing 

 many animals from making normal gains in weight. In many cases 

 there are indications that the presence of horn flies may be in part 

 responsible for the over-grazing of certain areas and the under- 

 grazing of others because of the animals' attempts to avoid the 

 flies. 



SHEEP TICKS (Melophagus ovinus) 



Sheep ticks often cause considerable loss in the sheep and 

 wool industries. They are common in all of the sheep raising areas 

 of Montana. Heavily infested flocks do not gain weight normally; 

 lambs are occasionally killed by the insects; and a poor grade of 

 wool is often produced. Sheep ticks are apparently more prevalent 

 at the present time than they have been in previous years. The 

 reasons for this increase in tick populations have not been estab- 

 lished. Many of the new insecticides show considerable promise 

 in controlling this pest, and growers, in general, have shown an 

 increased interest in sheep tick control. 



