250 Nebraska State Horticultural Society. 



bten had the operations begun earlier, making it possible to have useJ 

 a stroiiger emulsion, still the benefit derived was considerable in pro- 

 portion to the time and money spent. On examining some specimens 

 of twigs collected at the above named place in June, it was found that 

 90 per cent of the scales were dead, although just how much of this 

 mortality was due to the effects of the kerosene emulsion and hov/ 

 much to the moderately cold winter, was not determinable. On the 

 lot sent, three twigs six inches long, eight larvae of the predaceous 

 lady-bird were found. However, unless the natural enemies of the 

 pest are very abundant this year, the scales from unsprayed trees 

 will no doubt completely leinfest those sprayed, so that next year 

 they may again become abundant. If such is the case precautions 

 should be taken to go over all the trees during the coming winter^ 

 as the pest can be exterminated in this way; only temporary relief can 

 be had by spraying a portion of the trees. 



The treatment may take place any time after the trees have- 

 shed their leaves in the fall up to just before the buds appear in the 

 spring, preferably in December, .January and February. This method, 

 has many points of advantage over summer treatmiMit; in the first 

 place, as shown by Mr. S. Arthur Johnson* in some experiments 

 performed at Denver, Colo., it is the most effectual; secondly, the- 

 factor of economy is a favorable argument, it requiring only one-fourth. 

 as much material as is commonly used in spraying where the tree is iit 

 full foliage, and then, too, in summer spraying, owing to the fact that, 

 the young hatch out during a period extending over two months, at; 

 least two anplicalions would be imperative; lastly, it is a much less 

 difficult and disagreeable task to properly apply the insecticide, all 

 parts of the infested tree being visible. In a plant the leaves of which 

 are somewhat sensitive, as in the case of the box-elder, it is almost, 

 impossible to use a strong solution without defoliating the tree. Mr.. 

 Johnson in the exepriments cited above, found that the most satis- 

 factory remedies were a winter application of kerosene emulsion, of 

 a strength of 25 per cent or more, or whale oil soap at the rate of 

 one pound ler gallon; the lime-sulphur-salt solution was ineffectual.. 



Numerous other methods have been used in fighting this per- 

 nicious insect, such as spraying with a concoction made from boiling- 

 tobacco stems, fumigating with hydrocyanic gas. washing the scales 

 off by the use of a stream of water under pressure, etc., but all have 

 been practically abandoned in favor of the kerosene emulsion or 

 mechanical kerosene and water mixture. 



*Bullctin 52, U. S. Dept. Agric, Div. Ent., pp. 85-88. 



