INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



259 



Food Plants.— The foliage of sweet potatoes, bittersweet, morning' 

 glory and other species of Convolvulus are the common food plants of 

 this species. Professor C. W. Woodworth records the columbine and 

 encumber as food plants. 1 " 3 The adults are often taken on citrus and 

 other trees, but are probably only resting and not feeding upon them. 



Control.— Where this beetle is a pest of sweet potatoes it is advis- 

 able to dip the tops of the young plants when they are set out in a 

 mixture of arsenate of lead (1 pound to 10 gallons of water) and to 

 spray the plants afterwards with this mixture, if the beetles appear 

 after much new growth is made. 



THE BLUE MILKWEED BEETLE 



Ghrysochus cobaltinus Leconte 



(Fig. 251) 



Description. — This beetle may be recognized at once by the metallic 

 bine color which sometimes has a green iridescence. The body is 

 smooth throughout 

 and averages 

 nearly § inch in 

 length. Fig. 251 

 shows the shape 

 and general char- 

 acters. 



Life History.— 

 The i m mature 

 stages of this beetle 

 are not described, 

 but the larva? prob- 

 ably feed upon the 

 roots of plants, as 

 does a closely re- 

 lated species 

 (Ckrysochus a u - 

 ratus Fab.) . 1C4 The 

 adults appear in 

 the spring of the year and feed throughout the summer. 



Nature of Work. — The foliage is eaten in much the same manner 

 as by other leaf-eating beetles. 



Distribution. — The blue milkweed beetle is exceedingly common 

 throughout the entire State. 



Food Plants.— All species of milkweeds are the native and normal 

 food plants, but the beetle occasionally attacks oleander and orchard 

 trees. Peach trees 1 * 55 have been so injured. During the summer of 

 1914 the writer noted attacks on prune tree.s in the Santa Clara and 

 Sacramento valleys. 



Control.— The injury to fruit trees is so unusual as to make control 

 measures unnecessary. Poison sprays, applied when the beetles appear, 



103 Cal. Insects, p. 216, 1913. 

 '"Insect Life III, p. 349, 1891. 

 '"■Insect Life IIT, p. 163, 1896 



Fig. 251. — The blue milkweed beetle, Chrysochus cobaltinus 

 Lee. Adults, enlarged one and two thirds times. (Original) 



