EXPERIMENT STATION EEPOET. 



531 



surface with sap-filled cells; and as to the oil, it was certainly true 

 that a greasy coating remained long after the trees had started. 



But experience seems to indicate that trees are almost equally re- 

 sistant just before they become dormant, except against jfish-oil soap 

 and that the scales at that 

 time, being still in the 

 full tide of activity, are 

 much more susceptible. 



We know positively, 

 now, that the soluble pe- 

 troleum or emulsions will 

 cause no injury to fruit 

 buds or tree when applied 

 in late October and earl^' 

 November, and such W"! 

 as has been done with the 

 lime and sulphur com- 

 binations indicates the 

 same thing for them. 

 The K.-L. has been used 

 at almost all strengths 

 during summer and win- 

 ter, and should ])e no 

 more harmful than undiluted kerosene, which has been safely and 

 effectively used. 



My suggestion is, therefore, that the best time for spraying against 

 the scale is when the fruit is all off; when the foliage is mature — 

 just ready to drop — and while the scale is yet active. This period 

 will vary with locality and with the kind of tree. By the middle of 

 October, in the northern part of the State, peach trees may be treated, 

 and by the first of November apple trees will be ready. In the southern 

 section the scales have been found yet active early in December, but 

 such specimens stand no chance of surviving. 



No scale that begins to breed in fall lives through the winter, no 

 matter how few young she has born, and no fertilized female ready 

 to bear, survives. No larvae born after the sap has ceased to circulate 

 reach a stage that will carry them safely until next season. Only 

 those survive that reach the half-grown black stage, when the scale 

 is thickest and most closely applied to the trunk. These are the forms 



Fig. 3. 



An adult female scale from below : the real insect is below 

 and to the right, separated from its covering. 

 Much enlarged. From Bull. Va. Sta. 



