270 



NATURAL HISTORY oi- Till: FAR.\r 



from -^itliin. Those thus escape ])oisons (le])osiled upon the 

 surface of the plant, and are killed by spraying only when 



some contact in- 

 secticide (like kero- 

 sene emulsion, or 

 various ])rc]xira- 

 tions of nicotine, 

 etc.) is thro^vnupon 

 their bodies. 



Both types of 

 feeders we often find 

 side by side. We go 



Fk;. no. A colony of aphids on a leaf of Ceanolhiis' • -,^.„ „ ,.„uu^„p f,plJ 

 h a svrphus-flv larva, feeding- i, a wmged aphid; intOacaDDagC-neiQ, 



J^----\%-^^^^^ where Httle white 



butterflies flutter 

 above the rows, and we find their green lar\^ae, "cabbage- 

 worms," stretched at length upon the surfaces of the leaves 

 placidly eating out scallops in the margins 

 bage leaves we find whole colonics of ^ 

 minute gray-green aphids, "cabbage- 

 lice", sucking the sap out of the 

 leaves and making them buckle and 

 curl. 



Most herbivorous insects are very 

 limited in the range of their diet. 

 They will feed upon the plants of but 

 a few species — usually closely related s])ecies. The coniinon 

 potato-beetle eats other things besides ]X)tato, but only a 

 few other species of the same genus — other solanums. This 

 is, for the husbandman, a very fortu- 

 nate limitation. 



The worst of our field and garden 

 pests are species of insects fr<:)m 

 ''^IcJJ.^gflT'UrMaltt)! Other lands. They have been brought 



On loose cab- 



^•m 



Fig. 111. The nine-spottad 

 ladybird beetle and its 

 larva. 



