222 ANNUAL EEPORTS OF DEPAETMENT OF AGEICULTUEE. 



and in consequence definite results can not be looked for, in some cases, 

 for from 3 to 5 years. 



Clover-flower midge. — Investigations of the clover-flower midge, 

 taken up in western Oregon during the year, have been on the whole 

 very satisfactory, and the evidence shows that the growers of clover 

 seed may prevent attacks of this pest by properly timing the cutting 

 of their clover-hay crop and in such a way as not greatly to reduce the 

 yield. 



Clover-root curculio. — When the clover-root curculio was first 

 studied in 1909-10, it was not considered a very serious pest. It now 

 transpires that for years there has been an obscure injury to alfalfa for 

 which no one has been able to offer a satisfactory explanation. It has 

 been attributed to soil conditions, cultural methods, and various other 

 influences, and it is only within the last year that we have learned that 

 this damage is probably largely if not entirely due to the attacks of 

 the clover-root curcuho on the roots of alfalfa. The larvae feed on 

 the roots not only of clover, but of the plant kno^vn as sweet clover 

 ( Melilotus alba) . This is a roadside weed, and as red clover also occurs 

 abundantly along the roadside throughout the northern section of the 

 country, the control of the clover-root curculio in the alfalfa fields is 

 greatly complicated. 



CowPEA INSECTS. — Investigations of a number of insects attacldng 

 cowpeas were conducted as minor projects, but those relating to the 

 cowpea Cerotoma and the attacks of its larva on the nitrogenous 

 nodules of the plants constituted a major project. This work was 

 conducted in cooperation with the Bureau of Plant Industry, and 

 experinients were conducted on a large scale at the Arhngton Farm. 

 The object was to determine the effect upon the fertilizing value of 

 the cowpea of the destruction of the nodules by the larvc^ of the 

 Cerotoma. Unfortunately this beetle seems to be more abundant, 

 and its attacks on the nodules more serious, on the hghter lands 

 where the fertilizing element of the cowpeas is most essential to the 

 productiveness of the soil. The larvse of the cowpea Cerotoma cause 

 vastly more loss to the farmers than do the beetles. 



Grasshoppers. — During the year the bureau cooperated with the 

 Kansas Agricultural Experiment Station in conducting an extensive 

 campaign against grasshoppers, supervising the apphcation of the 

 poisoned bran bait over an area covering some 20 counties. In the 

 work on the grasshopper problem of the Merrimac and Connecticut 

 River Valleys it was found entirely practicable to destroy 95 per cent 

 of the grasshoppers present over considerable areas at an expense of 

 from 7 to 13 cents per acre by the use of a poisoned mixture. This 

 work was carried on in pastures where stock was grazing contin- 

 uously, but in no instances have any domestic or wild animals been 

 injured. Similar results were obtained in Florida against a local 

 grasshopper, and the farmers have made extensive use of the 

 discovery. 



Fall army worm. — ^During the year investigations conducted in a 

 number of States showed conclusively that the fall army worm does not 

 winter over north of extreme southern Texas and central or perhaps 

 to some extent northern Florida. If the pest is controlled in these 

 locahties by its natural enemies, its spread to the north as the season 



