REMEDIES AGAINST SCALE-INSECTS 91 



POPULAR METHODS AND REIVIEDIES. 



Cutting hack infested Trees. — The utter inadequacy of nearly all the 

 washes hitherto used has led many fruit-growers to despair of obtain- 

 ing permanent benefit from the application of remedies, and a common 

 practice has been to cut back badly infested trees, leaving only the 

 main trunks, or in the case of well-grown trees, a portion of the main 

 branches, and to scrub thoroughly every part of these with solutions of 

 soap or lye, using a stiff brush, and as far as possible removing every 

 scale. This, however, involves great care and considerable labor, and 

 the complete extermination of the pest is rarely accomplished in this 

 way. The loss of branches is indeed replaced with extraordinary rapid- 

 ity, bur, the Scale-insects reappear as if by magic, and in one or two 

 years become as bad as before. 



Fumigating. — Various plans have been proposedfor destroying Scale- 

 insects with pungent vapors of various kinds. The difficulties in the 

 way of applying vapors to trees growing in the open air are very great, 

 and appear to have been overlooked by the advocates of this method. 

 Tobacco smoke has been very frequently tried in inclosed greenhouses, 

 but although it will destroy Plant-lice (Aphis), it is found to have no 

 effect u])0u Scale-insects, which are far too well [)rotected by their tightly 

 sealed scales to be reached by vapors, except those of a corrosive na- 

 ture. 



Sulphur has been recommended, evidently on theoretical grounds 

 only, as its fumes are not less destructive to vegetable than to animal 

 life. The chlorophyl of the leaves and plants is bleached and the life 

 of a plant destroyed by a short exposure to any gas containing sulphur. 

 Actual trial of fumigation upon the Orange was made by covering a 

 young and vigorous plant with a barrel and exposing it for ten minutes 

 to the fumes produced by burning one ounce weight of sulphur. The 

 leaves were completely bleached and the plant killed. The Scale- insects 

 ujmn it (Long Scale) were uninjured by the sulphur vapor, and survived 

 until the bark became entirely dead and dry, i)erishing finally from 

 want of food and moisture. 



Apjjlicatiuns to the Boots. — No results of any value have been attained 

 by attempts to kill Scale insects through the juices of the plant by 

 uuiking applications to the soil with the expectation that they will be 

 taken up by the roots. Many nostrums are advertised and sohl as 

 insecticides, which it is claimed act in this way. There are also in the 

 market uot a few combined fertilizers and insect-exterminators, so- 

 called, to which is assiguetl a double action, beneficial in the case of the 

 plant, but deadly to the insect life which it supports. These claims are 

 based upon the assumed power of the plant to appropriate and mingle 

 with its juices unchanged the substances which have insecticide prop- 

 erties — an assumption wholly at variance with the known laws of vege- 

 table physiology. In fact an insecticide, if it could be introduced into 



