REMEDIES AGAINST SCALE-INSECTS. r5 



severe, according as their vitality is more or less iDipaired. Young, 

 tender shoots, budding leaves and blossoms, are not much affected by 

 kerosene, and may even be dipped in the pure oil with ini])unity. 



The heat of the sun increases to an injurious extent the action of 

 kerosene, and ai)plications of very strong solutions or undiluted kero- 

 sene, if used at all, should be made on cloudy days or at evening. 



Milk or soap emulsions containing CO or 70 per cent, of oil and diluted 

 with water ten times are more nearly harmless to the Orange than auy 

 other insecticide capable of killing the Scale-insect. Nevertheless the 

 plant receives a shock, imperceptible when the tree is in good condition, 

 but sufdciently severe when it is infested and injured by Scale to cause 

 the loss of the old, devitalized leaves. Complete defoliation and the 

 death of moribund twigs and branches may be expected to occur in ex- 

 treme cases. The shock is invariably followed by a reaction, and in ten 

 to fifteen days new growth appears. This growth is healthy and nat 

 ural, and if the application has been sufficiently thorough to destroy 

 the Scale-insect, results in permanent benefit. 



Enough has been said to show that kerosene is a powerful remedy, 

 perfectly effective and safe if used in moderation, but hurtful in strong 

 doses; that its use undiluted is attended with danger, is entirely un 

 necessary, and cannot be recommended. In Appendix II will be found 

 an examination of results obtained in experimental applications of kero- 

 sene, together with other insecticides, arranged in tabular form for con- 

 venience of comparison. 



The most favorable season for applying kerosene washes is undoubt 

 ediy early spring or as soon as all danger of frost is past. The shed 

 ding of the last year's leaves, w^hich takes place naturally after the 

 orange tree has renewed its foliage in spring, is often accelerated by 

 the action of the oil, which is thus made to appear very severe. But the 

 loss of old and devitalized leaves is of slight consequence, and in the 

 case of badly infested trees is a positive advantage, as the leaves in fall- 

 ing carry with them the scales most difficult to reach with insecticides. 



Whale-oil Soap. — This has long been considered one of the best inseiiti- 

 cides known, and is extensively used as a remedy for Bark-lice. Ex- 

 ])eriments show that very strong solutions kill the Coccids but have 

 little or no effect upon their eggs. Solutions of one pound of the soap 

 to three gallons of water failed to kill the adult Bark-lice or their eggs, 

 and did not destroy all the young. The strongest solution used, one 

 l)ouud of the soap to one gallon of water, killed all the Coccids and few 

 or none of the eggs. 



This solution solidifies on cooling, and must, therefore, be applied 

 hot. The effect upon the trees is about equal to that of effective kero- 

 sene emulsions; badly infested trees are somewhat defoliated, but new 

 growth and vigorous trees are not appreciably affected. As the eggs 

 are not killed, several applications at intervals of four to six weeks will 

 be required to clear a tree of scale. (See Appendix II, table 2.) 



