208 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



varying between 5 per cent and 20 per cent. Some of the eggs 

 hatched from all strengths used. 



The conclusion reached was that none of these oils can be depended 

 upon to kill eggs of plant lice, though the lice that hatch upon twigs 

 treated with the higher strengths very largely die from contact with 

 the oily surfaces after hatching. 



With these miscible oils, eggs of the same species were employed as 

 in the kerosene emulsion experiments. 



Soaps — Bowker's Tree Soap and Good's Whale-Oil Soap were used 

 for 77 different treatments in strengths varying from 2 pounds to 

 1 gallon of water down to 1 pound in 6 gallons. None of the eggs of 

 A. pomi, A. cornifolm, Ch. negundinis or Mel. smithke, which were 

 treated with 2 pounds to 1 gallon, hatched. Eggs of the same species, 

 and also of A. viburnicola hatched poorly when treated with a prep- 

 aration of 1 pound to 1 gallon. Weaker dilutions seemed entirely 

 valueless. 



Lime Sulfur Mixture made by the 15-15-45 formula was also 

 used against eggs of all the lice above mentioned and also those of 

 Myzus el(£agni. In this strength the lime-sulfur was a marked deter- 

 rent to hatching but all species hatched to some extent and some 

 rather freely. Weaker applications had little effect. Over 70 appli- 

 cations were made. Where strong lime-sulfur applications are made, 

 many lice die from contact with the lime-sulfur while struggling to 

 extricate themselves from the egg shell and others die after leaving 

 the shell and before taking food. 



I might add that eggs of Brijobia pratensis hatched freely after 

 thorough treatment with the 15-15-45 strength of this mixture. 



Rex Lime-sulfur was also used many times in one-fourth, one- 

 sixth, one-ninth, and one-twelfth full strength and with no better 

 results than were obtained with the home-made product just men- 

 tioned. 



Tobacco Extracts 



Black Leaf Extract was used twice in one-twentieth strength and 

 no eggs hatched. It was used 8 times in one-thirtieth strength and no 

 eggs hatched. Seven applications were made in one-fortieth strength 

 and in 5 cases none hatched, but in the 2 others a very few hatched. 

 Weaker dilutions did little good. 



Nikoteen was used 23 times in strengths varying between 1 in 100 

 and 1 in 500 parts and in only 3 cases did any lice hatch and these 

 were all Myzus elcEagni. The eggs of this species were the most 

 resistant of any used in the various tests. 



