14 MONTANA EXPERIMENT STATION J Jul. 139 



increase in the acreage of this new crop and should be mentioned 

 as a possible serious pest. 



Sugar-Beet Root-Louse (Pemphigus betae Doane). A substan- 

 tial increase over last year in the prevalence of this insect was noted. 

 Investigations conducted for a long period of years have shown 

 that even a moderate infestation of lice not only reduces the tonnage 

 but also cuts down the sugar content of the beets. 



BUTTERFLIES AND MOTHS (LEPIDOPTERA) 



Imported Cabbage Worm (Pcntia rapae Linn.). There was 

 more than the usual amount of damage by cabbage worms. People 

 generally have learned how to control this pest so that our large 

 number of inquiries indicates a great abundance of this pest this 

 season. 



Thistle or Painted Lady Butterfly (Vanessa oardui Linn.). This 

 insect played a dual role in its activities. Many larvae were found 

 to have destroyed the foliage of the Canada thistle (Carduus arven- 

 sis L.). an extremely noxious weed in some parts of the state, and 

 on the other hand great numbers of larvae ate so voraciously on 

 cultivated sunflowers that in some cases the defoliation of the plants 

 over many acres was almost complete. Of the insects that have 

 attracted attention as pests of cultivated sunflowers this one seems 

 capable of causing the most damage unless some control method is 

 developed by which it can be combated. 



Fruit-Tree Leaf-Roller (Archips argyrospila Walk.). See page 7. 



Diamond-Backed Cabbage Moth (Plutella maculipennis Cur- 

 tis). Cocoons enclosing the pupae of this species which were found 

 attached to the heads of wheat in several instances caused some con- 

 cern to farmers who feared they were threatened with a new wheat 

 pest. The inference is that the larvae fed on wild mustard growing 

 in the fields and crawled to the wheat heads to pupate. 



Codling Moth (Cydia pomcnella Linn.). Reports from the 

 Yellowstone Valley, together with a personal inspection trip, show 

 that this most important pest of the apple is becoming firmly estab- 

 lished in that locality. In the Bitter Root Valley the pest was much 

 worse than ever known before. Perhaps. the most serious damage 

 was done in the vicinity of Florence but orchards over the entire 

 district suffered much codling moth injury. In orchards which were 

 given the proper spraying gratifying results were secured. 



