MECHANICAL METHODS OF DESTROYING INSECTS 27 



Brushing methods.— Difiereni methods of brushing more or 

 less skiggish insects from their cultivated food plants have been 

 in vogue for many years. Potato beetles and their larvae may 

 be brushed from potato plants by means of a short-handled 

 broom, a second person to follow dragging by horse power a 

 bundle of brush or a harrow to crush the insects and bury them. 

 This process is simplified in the treatment of the asparagus 



Fig. 21^.— A canvas hopper-dozer to be drawn by horse, (After Riley) 



beetles. It consists in beating or brushing the insects from the 

 plants with a stick so that they will drop to the bare ground 

 on a hot dry day. The larvae are delicate creatures, crawl very 

 slowly, and few are able to regain the shelter of the plants and 

 die from exposure to the heated earth. A somewhat more com- 

 plicated system came into rather extensive use in 1900 against 

 the pea aphis. It is known as the brush and cultivator method, 

 and at the time of writing is the best remedy that has been de- 

 vised for this pernicious species. It will be described in dis- 

 cussing pea aphis remedies. 



Cloth covering. — To prevent injury from some forms of in- 

 sects to young plants before they are fairly above ground early 

 in the season cloth coverings are used. A cheap frame may be 



