Tenth Annual Report of the State 

 Entomologist of Montana 



INSECT PESTS OF 1912. 



While the season of 1912 was not marked by any unusually 

 severe outbreak of insect pests, yet several of our common pests 

 were more than normally abundant. In the lower Yellowstone 

 Valley occurred an outbreak of grasshoppers; in the sugar-beet 

 district, the sugar-beet web-worm was alarmingly abundant; while 

 over the entire State the Colorado potato beetle, the apple aphis, 

 and cut-worms occurred in more than usual numbers. 



For the sake of calling attention to and recording the economi- 

 cally important insects of the year, they are classified by orders 

 and briefly discussed. 



ACARINA 



Leaf Blister Mite (Eriophves pyri Pgst.). As usual many 

 letters were received reporting injury by this pest, both upon pear 

 and apple foliage. In Bozeman several mountain ash trees were 

 so badly infested that their foliage withered and fell in midsummer. 

 Spraying with lime-sulphur just as the buds are swelling is a sure 

 method of control. 



Plum Gall Mite (species undetermined). This little mite, which 

 causes small pocket-like galls on the upper surface of plum and 

 cherry leaves, is becoming increasingly abundant in eastern Montana. 



Parasitic Mite {Hemisarcoptes walus Shimer). This mite was 

 found feeding on eggs of the oyster shell scale in an orchard at 

 Lo Lo. Should it increase and spread sufficiently, it might prove 

 an important factor in controlling the scale. 



Chicken Mite {Dermanyssus gallhiae Redi). To comply with 

 the numerous requests for information concerning this pest a leaflet 

 has been prepared which outlines its life-history, habits and methods 

 of control. 



