INSECTS, HARMFUL AND OTHERWISE 



217 



terfly, seen flitting about every garden from early spring till 

 late in fall. The eggs are placed on cabbage, cauliflower, 

 and nasturtium leaves. The caterpillars are very voracious 

 and often do much damage. Pyrethrum powder (insect 

 powder) is a remedy. This butterfly is not a native species, 

 but was introduced from Europe about 1860, since which 

 time it has multiplied enormously, 

 having two or three broods a year. 

 A small ichneumon-fly is its para- 

 site, which in a measure acts as a 

 check to it. 



Plant-lice or Aphides, of which 

 there are many species, are harmful 

 to many plants. They are minute 

 insects, and their permanent loca- 

 tion on certain plants amounts 

 almost to parasitism, so much so 

 that most of them have no wings. 

 They are usually named after the 

 kind of plant on which they live: 

 cherry aphis, peach aphis, corn aphis, hop aphis, etc. They 

 are generally crowded together in great numbers on the 

 succulent twigs and leaves of plants. They live upon the 

 juices of the plant, which they suck through piercing beaks. 



Some aphides are green; others, black; some, red. Some 

 are covered with a woolly coat. Some have a pair of little 

 rods at the rear end of the back. These aphides excrete a 

 sweet liquid, which often drops from them upon the leaves 

 and the walks beneath the trees. This liquid is called 

 honey-dew, and is relished by certain ants, which may often 

 be seen in summer among clusters of black aphides on the 



FIG. 73. Plant-lice. 



