BUEEAU OF ENTOMOLOGY. 403 



A study has been conducted on the distribution and habits of the 

 ■cabbage flea-beetles and some species have been the subject of special 

 investigation in Louisiana. Nicotine dust gives some promise as a 

 control means. 



Insects injurious to strawberries. — Investigations in the con- 

 trol of the strawberry weevil have been continued in New Jersey 

 and South Carolina, and in both States the value of proper ar- 

 senical combinations with sulphur applications has been demon- 

 strated. In Louisiana additional studies have been conducted in 

 the control of the strawberry flea-beetle, Haltica litigata Fall, which 

 has within the past few years become a serious pest on strawberries 

 in that State. Further work is being conducted in the control of 

 the red spider on strawberry in Louisiana. It has been learned 

 that the unfavorable weather conditions existing in the spring 

 Tender it almost impossible to control this insect at the time when it 

 is in greatest abundance and most injurious to strawberry. Biologi- 

 cal studies, however, indicate that it may be possible to obtain 

 practical control by application of insecticides in the fall. 



Sugar-beet insects. — Work on the curly-top leafhopper in co- 

 operation with the Bureau of Plant Industry has been continued 

 in southern California. Further studies in the life historj^ of this 

 insect and the relation of wild food plants to its destructive 

 abundance are being followed. The production of disease-resisting 

 strains is still receiving attention and some promising preliminary 

 results have been obtained. Life-history studies of the beet army- 

 ^'orm in its occurrence on peas in California are being continued. 



Nicotine dust investigations. — The importance of nicotine dust 

 as a means for the control of various truck-crop insects has led to 

 a continuance of studies of this insecticide. The relation of va- 

 rious carriers to the effectiveness of nicotine dusts is being tested 

 in California, Louisiana, Maryland, Virginia, and Wisconsin. Such 

 tests have considered the mechanical value of different compounds, 

 in addition to their absorptive qualities and the varying rates at 

 "which they cause volatilization of the nicotine. 



General truck-crop insects. — In South Carolina the Porto Rico 

 mole cricket, recently introduced in that State, has continued to be 

 the subject of investigations with poisoned baits with gratifying 

 success. In Louisiana additional work has been conducted on the 

 southern green plant-bug, Nezara vividula L., but a perfectly effec- 

 tive method of control has not yet been developed. Work has been 

 •done on the control of the onion thrips in Texas, with especial at- 

 tention to the value of nicotine dust as a remedy, and additional 

 work has been conducted on the onion maggot in its occurrence in 

 Wisconsin. Some work has been begun and will be continued on 

 •dusting with calcium arsenate or arsenate of lime on a number of 

 insects in comparison with other arsenicals and nicotine dust, since 

 it contains a stronger arsenic content than lead arsenate and can 

 be obtained cheaper. As soon as it is on the market more exten- 

 sively it will probably replace lead arsenate at nearly half the cost. 

 The results thus far obtained are very promising. 



