54 



be due to lack of fertilization, as the little wingless brown males occur 

 in large numbers and freely copulate ^itli the females during the fall. 



The cabbage louse {Aphis hrassicce) seems to be a worse pest upon 

 cabbages and cauliflowers than the cabbage butterflies, P. rcqjce and 

 P. protodice. 



The beet army worm (Lapliygma flavimaculata), which ravaged the 

 sugar-beet fields to such an alarming extent in the Grand Valley in 

 the summer and fall of 1899, was almost entirely absent over the 

 same area in 1900, in spite of the fact that the moths emerged in 

 enormous numbers late in September for hibernation. Thej' did 

 occur in considerable numbers last year, however, in the ^^.cinity of 

 Rockyford. Colo., where sugar beets were being grown for the first 

 time in large numbers for commercial purposes. The past summer 

 the first brood of this insect appeared in considerable numbers, both 

 at Palisade, in the Grand Valley, and in the Arkansas Valley in the 

 vicinity of Lamar. It is now time for the second brood to be on in 

 full force, but I have heard nothing of it yet. It looks as though 

 another native insect, formerly unknown as a destructive species, had 

 come to stay as an enemy to beet culture. 



The cabbage Plutella(P. cruciferariim). — A curious instance in the 

 food habits of this insect was called to my attention the present sum- 

 mer. Mr. H. E. Mathews, horticultural inspector for Delta County, 

 sent me a quantity of leaves from small peach trees, Avith hundreds of 

 small white cocoons upon them, with the statement that some new 

 peach defoliator had appeared in an orchard in Delta County and he 

 Avished me to tell him what to do about it. I could not tell what 

 the insect would turn out to be. but in a few days moths of the cab- 

 bage Plntella appeared in large numbers, and I was almost as much 

 puzzled as before. I told Mr. Mathews the ordinary food habits of 

 the insect, and then he exi)lained that the year previous the ground 

 in this orchard had been allowed to grow up to a wild mustard, and 

 that the weeds had been thoroughly kept down this summer. The 

 moths, doubtless, hatched there in large numbers and, not finding 

 their natural food plants, deposited eggs upon peajCh leaves, upon 

 which the larvse developed. (Photographs of the cocoons of this 

 insect upon peach leaves were exhibited.) 



The thistle butterfly {Pyrameis cardui) was unusually abundant 

 throughout the State while fruit trees were in bloom, so that many 

 inquiries were made as to the significance of this insect in such 

 numbers. 



The bean ladybird {Epilachna corrupia) does considerable damage 

 to the foliage of beans, particularly wax beans, near the foothills of 

 the east slope of the mountaius every year, but the degree of destruc- 

 tiveness varies much. The present season the injuries have been 

 more severe than for several years past. It is also difiicult to combat 

 on account of the beans being very susceptible to injury from the 



