



In inilkueed I In i .m< efl U 



cntly upon several species of plant- pn.\ided tin attri- 



in common. 'I 'lui- AfgynnU < v/v/r, >i />Jir<><Jitc and <itl>uiti\ rat the 

 various >pccie- of violet -, and the ( 'olorado potato beetle eats 

 different -pet -ie- of Sohinutu. J'<i />ilio tli<> upon n: :i<kly 



a-h and other Kutacca-. .\noxi<i plrxi />/)ns eatfl the van 



'>/</.v and also . 1 /UK ynum androsamifolium; whili ////.? also 



is limited to these two genera of |>lant 



in having a milky juic'e; in fact the two genera are rather nearly related 

 licallv. Tlu' common cabbage buttertly i /'/Vm r^ifxr, though con- 

 tined for the most part to Crucifene, such as cabbage, mustanl, turnip, 

 nulish, horse-radish, etc., often dcvel- A 



op- upon Tropiroliou, which belongs to 

 all its food plants, how- 

 . have a pungent odor, which is 

 probably the >timulus to oviposition. 



Most phytophagous insects range 

 over many food plants. The cecropia 

 caterpillar has m9re than sixty of 

 tlu>e. representing thirty-one genera 

 and eighteen orders of plants; and the 

 tarnished plant bug (Lygus pratensis) 

 - indifferently on all sorts of herb- 

 age, as does also the caterpillar of Dia- 

 crisia I'irghiica. Many of the insects 

 of apple, pear, quince, plum, peach, 

 and other plants of the family Rosaceae 

 occur also on wild plants of the same 



family; and the worst of our corn and wheat insects have come from 

 wild grasses. As regards number of food plants, the gipsy moth "holds 

 the record," for its caterpillar will eat almost any plant. In Massachu- 

 setts, according to Forbush and Fernald, it fed in the field upon 78 

 species of plants, in captivity upon 458 species (30 under stress of 

 huiiLrer, the rot freely), and refused only 19 species, most of which 

 (such as larkspur and red pepper) had poisonous or pungent juices, 

 or were otherwise unsuitable as food. The migratory locust is noto- 

 riously omnivorous, and perhaps eats even more kinds of plants than 

 .'ipsy moth. 



Galls. Most of the conspicuous plant outgrowths known as "Balls' 1 

 are made by insects, though many of the smaller plant galls are made 



FIG. 25j. Holcaspis globulus. A, 

 galls on oak, natural size; B, the gall- 

 maker, twice natural length. 



