REPORT OF THE SECRETARY OF AGRICULTURE. 29 



CONTROL OF INSECTS. 



While all the State Experiment Stations support work in economic 

 entomology, and while many other countries are developing services 

 in this direction, the Department of Agriculture has by far the largest 

 organization for the purpose of research on insect pests. It is virtu- 

 ally the leader of the world in the warfare against injurious insects. 

 It has in its files biological notes on thousands of species and is study- 

 ing them from all points of view in its field laboratories. No less 

 than 143 distinct projects are being investigated at the present time, 

 involving possibly 500 of the species of insects most injurious to 

 crops, domestic animals, stored foods, forest products, shade trees, 

 and ornamental plants. It is safe to say that some form of remedial 

 treatment has been found for every markedly injurious insect in the 

 United States, but continued efforts are being made to find some- 

 thing more effective or cheaper or simpler. 



Many striking things have been accomplished. The pear thrips, 

 which at one time threatened the extinction of the Pacific coast de- 

 ciduous-fruit industry, is no longer feared. Two serious pests of the 

 clover-seed crop now can be handled by slight variation of cropping 

 methods. The bark-beetles of our coniferous forests, which have 

 imposed a loss comparable to that resulting from forest fires, can be 

 controlled at very little expense. Sprays and spraying machinery 

 have been developed which can be used successfully against practi- 

 cally all leaf- feeding species. The fumigation of nursery stock and 

 of warehouses has been perfected. Such injurious species as the 

 onion thrips, the grape-berry moth, the alfalfa weevil, the tobacco 

 hornworm, and many others of recent prominence, can be con- 

 trolled. The spread of the gipsy and brown-tail moths through our 

 northern forests and orchards has been prevented. These injurious 

 insects not only have been kept in a comparatively small territory, 

 but are being reduced in number year after year by active scouting, 

 spraying, banding, and egg destruction, and through the aid of para- 

 sites brought from Europe and Japan. Although the spread of the 

 cotton boll weevil — which represents probably the most difficult 

 problem in insect control — has not been stopped, the investigations of 

 the department's entomologists have shown the southern planter how 

 to reduce greatly the potential damage and how to grow cotton in 

 spite of the weevil. 



