206 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



ber of eggs are laid. In September and October the adults again 

 become numerous and these adults are evidently the ones which live 

 over the winter. After August very few eggs are laid; however, dur- 

 ing most of the year all forms may be found in the soil. From the 

 above it is apparent that there are at least two generations a year, under 

 greenhouse conditions. 



Experiments in Control of Soil Stages 



In view of the fact that the larval and pupal periods, which require 

 from six to eight weeks, are spent in the soil, our efforts during the 

 first season were largely directed to the finding of some soil application, 

 either an insecticide or a fertilizer, which would operate against these 

 stages and hence prevent the emergence of the adults. With this ob- 

 ject in mind the following materials were tried out during the season of 

 1920. 



a. Carbon bisulfide — 5 to 25 cc injected between bushes approximately 14" 

 apart. 



b. Carbon bisulfide in solution — X to % ounce dissolved in four gallons water 

 applied to twenty-four square feet. 



c. Sodium cyanide in solution — Y^ to yi ounce per gallon ot water applied to six 

 square feet. 



d. Cyanamid — }i to 2 lbs per 40 sq ft. 



e. Acid Phosphate— 200 lbs to 1200 sq. ft. 



f. Wood Ashes— 200 lbs to 1200 sq. ft. 



g. Tobacco Dust— 200 lbs. to 1200 sq. ft. 

 h. Hydrated Lime— 200 lbs to 1200 sq. ft. 



The above applications were based on one plant per square foot. 



Applications of the last five materials were followed by thorough 

 watering to insure prompt leaching of the active elements. Consid- 

 ering both plant tolerance and insecticidal value, the acid phosphate, 

 wood ashes, and tobacco dust were the more promising. 



In the season of 1921 an excellent opportunity presented itself for 

 further experimental work along this line. At a wholesale rose estab- 

 lishnemt at Doylestown, Pa., a ground bed containing approximately 

 800 plants heavily infested with soil forms of Paria caviella was placed 

 at the disposal of the writers. It is interesting to note that these plants 

 had been growing in this bed for eight years which may account for the 

 extremely heavy infestation, where around the roots of some plants 

 as many as twenty-three (23) individuals were found. 



Preliminary tests were first conducted with potted rose plants in 

 which a definite number of larvae and pupae from the infested bed were 

 buried at their normal depth. The effectiveness of the following ma- 



