168 THE BOOK OF THE ROSE chap. 



of increase, and it is only in multitudes that they do 

 any harm. In their anxiety to obey the command 

 to increase and multiply, the presence of males is 

 postponed as a useless luxury till the season is 

 nearly over. In the meantime each individual, as 

 soon as full grown, which will be in favourable circum- 

 stances when about a week old, begins to produce 

 young ones ready to commence juice-sucking at once, 

 at the rate of dozens or so a day for weeks. In 

 this manner it is said as many as seventeen gener- 

 ations may be produced before the males appear, 

 and it is calculated that the descendants of a single 

 aphis in one season might thus be reckoned by 

 millions. 



Strength, vigour, and cleanliness in the plants 

 seem to be the best preventive measures. It may 

 appear strange that vigour and health should keep 

 off an insect foe, which we should fancy would be 

 naturally congregated where there was the greatest 

 abundance of sap for food, but though they are to 

 be found on healthy plants, it will, I think, be 

 generally allowed that the weaker ones are the most 

 attacked. 



Destructive and remedial measures are many and 

 various. Almost every insecticide known is adver- 

 tised as destroying them ; and no wonder, for they 

 are delicate creatures with no power of escape, and 

 are easily killed. The golden rule for all pests — 

 attack the first symptons with immediate vigour- 

 is especially applicable in this case. A constant 

 look out, and crushing every one as soon as seen, 

 never leaving it till to-morrow, is the remedy for 

 aphides. 



Of all instruments and apparatus for the destroy- 



