120 



are able to increase rapidly or after they have done the main part 

 of their work. If these Aleurodids are scarce, it may be advisable to 

 permit the fungi to act throughout the rainy season, and to spray 

 when this is over. The fundamental principles relating to the control 

 of whiteflies are mainly applicable to the purple scale [Lepidosaphes 

 beckii] also, except that the third brood of the citrus whitefly [Dialeu- 

 rodes citri] deposits eggs in August and early September, the adults 

 emerging the following March, and it therefore does not multiply or 

 reproduce during this tim.e. L. beckii reproduces during this entire 

 period, the rate depending on the temperature. The author suggests 

 that steps should be taken to discover predacious enemies or Hymenop- 

 terous parasites that would control the purple scale from January to 

 June, thus supplementing the action of the fungi. Until such know- 

 ledge is available, spraying should supplement this in the warmer 

 sections of the State. 



In discussing the fundamental principles of artificial control, it is 

 shown how the cost of such control may be compared with the expected 

 profits. The first brood of whiteflies is in the most susceptible 

 stage about the middle of April, but as the fruit is then extremely 

 small and sensitive, oil spraying should be postponed. Spraying 

 against this pest should not be undertaken until the eggs have hatched. 

 L. beckii is usually present in all stages throughout the year, but more 

 hatching takes place in March and the third week in June and in 

 September. If the scale is abundant, the last week in June will be 

 the most effective date for spraying. 



Rust mites are mainly injurious in May and June. On grape- 

 fruit they appear somewhat earlier than on oranges. It is now known 

 that soon after the rainy season begins a virulent fungus appears that 

 practically exterminates the mites. Spraying should be undertaken 

 before their maximum infestation, which is about May and June, 

 but the author doubts the profitableness of spraying before the rainy 

 season. 



It is not certainly known what kind of oil makes the best insecticide. 

 It is usually thought that an oil possessing high viscosity and low 

 volatility is the most effective in killing insects. For a severe infesta- 

 tion of purple scale an oil of high viscosity may be suitable, while a 

 lower viscosity may be used for whiteflies. Information is also 

 given on sulphur sprays, machinery and other necessary appliances. 



MozNETTE (G. F.). U.S. Bur. Ent. Notes on the Royal Palm Bug. — 



Qtrly. Bull. Florida State Plant Bd., Gainesville, vi, no. 1, October 

 1921, pp. 10-15, 3 plates. 



The Lygaeid, Xylastodoris luteolus, Barber, has recently been causing 

 serious damage to royal palms [Oreodoxa regia) in Southern Florida. 

 It has been previously reported from Cuba, but this appears to be 

 the first record of its occurrence in the United States. The bug 

 attacks young leaflets wrapped up in the spike and the folded leaflets 

 on the leafstalk as it gradually opens. Its attacks result in the dying 

 and browning of the injured portions. 



The remedial measure recommended is spraying with one part 

 nicotine sulphate (40 per cent.) to 1,200 parts water. To this diluted 

 spray fish-oil soap was added, using 5 lb. to a 125-gallon tank. Two 

 applications should be made, with a week's interval. 



