317 



phase and males in the sexual. Thus there is a transition from a 

 preponderance of apterous females early in the cycle to a preponderance 

 of winged females later, and in the sexual part of the cycle, a 

 transition from males to sexual females, these transitions implying 

 a gradual change of some sort, probably in the metabolism of the 

 insects. 



It may be that the metabolic change that causes the transition from 

 wingless to winged females is different from that causing the transition 

 from males to sexual females, and these may be more or less inde- 

 pendent of each other, and capable of being separated experimentally. 



YoTHERS (W. W.). The Mixing of Oil Emulsions with Lime-sulphur 

 Solutions. — Florida Grower, xviii, no. 18, 1918, p. 4. (Abstract 

 in U.S. Dept. Agric. Expt. Sta. Record, Washington, D.C., xl, no. 

 5, April 1919, pp. 454-455.) 



The use of oil emulsions mixed with lime-sulphur solution [see this 

 Review, Ser. A, vi, p. 449] is reported on. 



In following the directions given it was found that a granular scum 

 was formed when the glue and misoible oil combination was added to 

 the lime-sulphur solution, and though on stirring a fairly good mixture 

 was formed, the use of an agitator was necessary when applying it, in 

 order to prevent the scum settling to the bottom and forming a 

 concentrated solution that is injurious. 



The results of spraying tests indicate that glue must be added to 

 the oil emulsion when it is being made, whereas it can be added after- 

 wards to a miscible oil. With a view to determining the effect upon 

 w'hiteHyl Ale urodes]a.nd purple scale [Lepidosaphes beckii], experiments 

 were made in which miscible oil was stabilised with (i) glue solution 

 and (ii) milk powder. A stabilised emulsion was also used in place 

 of the miscible oil, and the glue solution was used for a binder. 

 It was found later that the addition of glue to a stabilised emulsion was 

 unnecessary. Whitefly pupae were killed perfectly, and the sooty 

 mould was loosened and fell oil after the first rain. At the time of 

 writing the sprayed trees were free from sooty mould and purple scale 

 and had a much better appearance than a control row of unsprayed 

 trees in the same grove. It is pointed out that while the mixture 

 seems to be satisfactory as an insecticide, it may injure the trees and 

 fruit. 



There is no evidence to show that the combination of oil emulsions 

 and lime-sulphur is superior to a combination of the emulsion and 

 soda-sulphur solutions. Until further knowledge has been obtained, 

 it would therefore be well to try the former combination experimentally 

 only. 



Smith (R. E.). Walnut Worm threatens Industry. — Cat Cult. \i, no. 

 18, 1918, pp. 441, 442, 447, 6 figs. (Abstract in U.S. Dept. Agric. 

 Expt. Sla. Record, Washington, B.C., xl, no. 5, April 1919, pp. 

 456-457.) 



The author calls attention to the fact that a biological variety of the 

 codling moth [Cydia pomanella] is seriously injuring walnuts in certain 

 parts of California, and that the immediate inauguration of remedial 



