458 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Natural Enemies. 323 — Internal parasites which attack the ehrysalids 



are important factors in the reduction of the numbers of the cabbage 

 worm. In California the hymenopterous parasite, Pteromalus puparum 

 Linn., is quite widely distributed and often quite effective. Apanteles 

 glome ratus Linn, is common in the Eastern States, and was recently 

 introduced into California by the State Insectary. Wolf's ambush bug, 

 Phymata wolfii Stal., destroys the butterflies, while the wheel bug, 

 Arilus cristatus Linn., the spined soldier-bug, Podisus maculiventris 

 Say. and the wasp, Polishes pallipes LepeL, are predaceous upon the 

 caterpillars. The tachina fly, Exorista vulgaris Fall., is parasitic upon 

 the larv;v. 



THE ALFALFA CATERPILLAR 21 



Eurymus eurytheme (Boisduval) (Family Pieridae) 



(Colias eurytheme Boisduval) 



(Figs. 469-471) 



Description. — The predominating color of the butterflies is a rich 

 orange-yellow, reddish-yellow or sulphur-yellow, though some are much 

 lighter. The upper outer margins of the wings are dark and there 

 is a black spot near the front margin in the middle of the front wings 



and a deep orange 

 spot near the middle 

 of the hind wings. 

 The antenna? are red- 

 d i s h with dusk y 

 knobs. The length ot 

 the females is about 1 

 inch, with a wing ex- 

 panse of 2 inches. 

 The males are slightly 

 smaller. The eggs are 

 very minute, dis- 

 tinctly r i b b e d and 

 cross-lined, white 

 when first laid, be- 

 coming brownish with 

 age. They are de- 

 posited upon the new 

 growth. The cater- 

 pillars are about 1 inch long and dark green in color with a distinct 

 and sometimes a faint white line on each side. The openings of the 

 spiracles are black and red. The dorsum is often darker than the 

 remainder of the body. The pupae are yellowish-green, | inch long 

 and suspended to the stalks, head up. 



Fig. 469. — Larva? of the alfalfa caterpillar, Eurymus 

 eurytheme (Boisd.). Natural size. (Original) 



•^Insect Life, III, p. 16. 1S90. 



Chittenden, F. H., Cir. No. 60, Bur. Ent, U. S. Dept. Agric, 1905. 

 'Wildermutli. V. L., Cir. No. 133, Bur. Ent. Dept. Agric, 1911, and Bui. No. 124, 

 U. S. Dept. Agric. 1914. 



The light sulphur-yellow butterflies have usually been considered a distinct species, 

 Eurymus philodice (Godart), but are now thought to be but a color phase of the 

 alfalfa caterpillar. (Bui. 124, U. S. Dept. Agric, p. 14, 1914.) 



