BUEEAU OF ENTOMOLOGY. 643 



have turned out to be the best are nicotine solutions with whale-oil 

 soap, strong turpentine soap, lysol, and lime-sulphur. Kerosene 

 emulsion was used to some extent, but owing to the amount of lime 

 in the water it was difficult to secure a stable emulsion. The main 

 object of this investigation has been to find some means of holding 

 the thrips in check so that the plants maj^ mature normal bulbs. 

 Many growers have sprayed too late, not beginning until after the 

 plants have begun to curl. After such a check in growth has gone 

 on for several weeks spraying is practically useless, unless excessive 

 rains occur, in which case possibly one-third of the crop will mature 

 to a normal degree. Some of the growers have succeeded in holding 

 the thrips in check with only two sprayings, while others have had 

 to spray as many as seven times. It is hoped that the next season's 

 work will result in a lessening of the number of applications needed 

 and in the use of machines that will cover more than one row at a 

 lime. It is estimated that 25 per cent of the onion crop in Texas 

 was lost through the work of this insect during the season of 1910-11. 



INVESTIGATIONS IN SOUTHERN CALIFORNIA. 



A laboratory for the study of truck insects has been maintained 

 at Compton, Cal., and much new information has been gathered con- 

 cerning the insects affecting truck crops and sugar beets. The bean 

 thrips, among others, has been carefully studied, and its habits, life 

 history, and control have been fully worked out. An interesting in- 

 ternal parasite has been found which is also parasitic on the onion 

 thrips, the percentage of parasitism often reaching 30 to 50 per cent. 

 It has been demonstrated that this parasite can be successfully trans- 

 ported elsewhere by shipping the dormant parasitic pupro. Attempts 

 are being made to introduce it into other sections of the United States 

 in which the onion thrips is causing damage. 



Cutworms and wireworms infesting sugar beet have been carefully 

 studied and an investigation of the beet root-aphis has been con- 

 tinued. 



Work on the celerj^ leaf-tyer has been nearly completed, and it 

 has been shown by chemical analyses of sprayed celery that there is 

 no danger to the consumer from celery sprayed with arsenicals. 



INVESTIGATIONS IN NORTHERN CALIFORNIA. 



With headquarters at Sacramento, Cal., investigations were con- 

 ducted upon the red spider of the hop. the hop aphis, cutworms, and 

 the white ants attacking trellis poles. 



A good means of fighting the so-called rod spider has been worked 

 out. This consists of mixing lime-sulphur with floui" paste, after- 

 wards diluting it. This mixture kills the eggs of the mites, whereas 

 jjowdered sulphur did not have this effect. Two applications were 

 necessary thoroughly to reduce the infestation. 



Observations were made upon the hop aphis at Santa Kosn. with 

 espocial reference to its hibernation, and sjiraying experiments were 

 carried on to determine the efficiency of various proportions of 

 nicotine sulphate and whale-oil soap, blackleaf tobacco with whale- 

 oil soap, and whale-oil so«ip alone. 



