INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



461 



Nature of Work.— The caterpillars devour the leaves, thus defoli- 

 ating portions or entire trees. 



Distribution. — This species is commonly distributed throughout the 

 State. 



Food Plants. — 



Balm of Gilead, 

 birch, elm, hack- 

 berry, linden, pop- 

 lar and willow are 

 among the food 

 plants. 



Control. — The 

 application of poi- 

 son sprays as soon 

 as the caterpillars 

 first appear in the 

 spring will easily 

 control this pest. 

 Cutting and burn- 

 ing the branches 

 upon which a col- 

 ony is located will 

 often exterminate 

 a small infestation. 

 These control 

 measures would 

 not justify the 

 costs, except in 

 small gardens. 



Fig. 472. — Larva and adult of the mourning cloak butter- 

 fly, Euvanessa antiopa (Linn.). Natural size. (Original) 



THE THISTLE BUTTERFLY 



Vanessa cardui (Linnaeus) (Family Nymphalidae) 323 



[Pyrantels cardui (Linnaeus)] 



(Papilio cardui Linnaeus) 



(Fig. 473) 



Description. — The butterflies are deep orange or red with white, 

 black and dark brown markings, as shown in the illustration (Fig. 478 >. 

 The length is about 1\ inches and the wing expanse is 2 inches. The 

 full-grown caterpillars are black or dull brown with a distinct pale or 

 yellow stripe on the side. The spines are rather long and forked, as in 

 all larva? of the nymphalids. The length averages from H inches to 2 

 inches. The chrysalises are iridescent brown, or appear as if dipped 

 in molten gold. They are about 1 inch long. 



Life History. — The adults appear in the spring and deposit 



"'This species is generally replaced in the central and northern parts of the State 

 by a closely related species, Vanessa caryce Hiihn. It is distinguished by a black 

 band across the cell of the front wings. 



