INJURING THE LEAVES. 161 



or meal, which they throw out from numerous minute 

 pores along the sides of their bodies. This serves 

 both as a protection from enemies, and also as a place 

 of concealment for the eggs of the insects. 



Woody green-house plants, such as the Oleander, 

 Orange, Abutilon, etc., are also often infested with 

 scale insects that occur upon the stems, sucking out 

 the sap and so absorbing the vitality of the plants. 

 These belong to the same family of insects as the 

 mealy-bugs, to which they bear a general resem- 

 blance in life-history and habits. 



Remedies. — When a plant is once badly infested 

 with either of these j)ests it can be cleared only by 

 thorough and careful work. As many should be 

 rubbed or brushed off by hand as possible, and then 

 the plant may be sprayed with kerosene emulsion, 

 which, however, should be used with caution on the 

 more tender varieties of greenhouse plants. It is 

 not necessary to treat the whole plant, but only the 

 parts infested by the insect. In case only a few 

 mealy-bugs are present they may be killed by dip- 

 ping a small brush in alcohol and then saturating 

 the colonies of the insect with it. Or the affected 

 part of the plant may be washed with a forcible 

 stream of water till all signs of the insects or their 

 eggs are removed. Professor Comstock reports an 

 experiment in which equal parts of smoking tobacco 

 and flowers of sulphur were ground together in a 

 mortar until thoroughly mixed, and the compound 

 thus formed was dusted over wet infested plants, and 

 the mealy bugs destroyed. 



