242 ANNUAL EEPORTS OF DEPARTMENT OF AGRICULTURE. 



INSECTS AFFECTING GROWING BEANS AND PEAS. 



An investigation of the bean ladybird — an insect which is to the 

 bean crop of Colorado, New Mexico, and neighboring States what 

 the Colorado potato beetle was to the potato crop in earlier years — 

 was undertaken, and the results are available for publication. Addi- 

 tional experiments, however, are necessary for the control of this 

 insect in order to lessen damage to the crop by the means of control 

 themselves. 



The pea aphis has been studied in California, as well as a pea moth 

 which has been introduced during the year into Wisconsin, and two 

 species of borers which affect especially Lima beans, one in the 

 Southern States and the other in the Pacific region. Enormous areas 

 in Lima beans and other beans were planted this year in southern 

 California, and there has been a severe and unusual outbreak of the 

 corn earworm upon the bean pods in that part of the country, neces- 

 sitating careful studies of the conditions which have brought about 

 the damage in the hope of preventing it another year. 



OTHER TRUCK-CROP INSECTS. 



The problem of the control of the onion thrips has been solved, 

 and the department is now able to prescribe practically new methods 

 of treatment which give excellent results. Some progress has been 

 made in the control of the onion maggot by the use of sweetened 

 sodium arsenate and arsenite in the destruction of the adult flies 

 while depositing their eggs. 



In the same way insects injurious to crucifers, such as the cabbage 

 aphis, the false turnip aphis, and the harlequin cabbage bug, have 

 been studied. The last-named pest, ordinarily an important one 

 throughout the South, was largely controlled by the cold winter of 

 1918. 



Work on insects injurious to strawberry, blackberry, raspberry, 

 and related plants of the rose family has been continued in several 

 States, and good results have been accomplished iii the line of con- 

 trol of the leaf-rollers by arsenical spraying. A saving of at least 

 50 per cent was made in experiments in Iowa, and in Kansas a single 

 spraying resulted in destroying two-thirds of the pests. 



Investigations of insects as agents in the transmission and over- 

 wintering of the disease of cucurbit vegetables known as "inosaic" 

 have been continued in Indiana arid Wisconsin. Hundreds of indi- 

 vidual insects were used in hibernation experiments, and about 100 

 experiments in control by insecticides are now under way. 



The principal investigations of the insects affecting sugar beets 

 have led toward the solution of the problem presented by the annual 

 damage from the curly-top disease. It has been shown that a leaf- 

 hopper is the agent responsible for the transmission of this disease, 

 and studies of the life history and economy of the insect carrier have 

 been nearly completed. These have led to experiments in the time 

 of planting which have yielded results of such value that their appli- 

 cation to commercial plantings will probably insure a paying crop 

 in infested regions. 



