8 BULLETIN 535, U. S. DEPARTMENT OF AGRICULTURE. 



of the species. In 1000 A. B. Wolcott (5) made mention of the cap- 

 ture of the beetle at Bloomington, 111. Injury by this species was 

 briefly mentioned by J. J. Davis in Illinois in 1910 (6). In 1910, also, 

 Blatchley (7) recorded its occurrence in Lake County, Ind., and in 

 1911 A. F. Winn (8) observed it at Westmount, Quebec, Canada, on 

 horse-radish received from Montreal. It is not stated, however, 

 whether the insect Avas believed to come from Montreal or from 

 Westmount. In Europe brief notes were published by Heikertinger 

 in 1911 and 1912 (9,10). 



FOOD PLANTS. 



This beetle is partial to horse-radish and marsh cress. It was taken 

 once on young cabbage in hotbeds in early spring by the junior author 

 but was not observed to be eating. The future no doubt will reveal the 

 possibility at least of other host plants. 



SEASONAL HISTORY. 



THE EGG. 



The eggs are deposited from the latter part of April or early May 

 through spring and summer until early August. The manner of 

 placing and the position are variable, but the preferred location is on 

 the tender petioles of young leaves, in the crevices where they leave 

 the root. A few eggs have been found on the ground and on different 

 places on the leaves, above and below the ground, and also carefully 

 placed in the pits made in the stems and petioles by the larvae or 

 adults. They usually occur in small masses, either carefully arranged 

 side by side in single rows, or two rows high, or carelessly piled with- 

 out order. Occasionally an egg is found standing on end. The 

 attachment to the plant is not very secure and often an egg-mass falls 

 on the slightest disturbance. In the cages from 2 to 26 eggs were 

 laid at intervals by a single female. "While the most frequent number 

 of eggs deposited was 22, at times 44 were deposited, indicating that 

 about 22 eggs are developed in the ovarian tubes at one time. Copula- 

 tion often takes place between deposition of batches of eggs, but it 

 has not been determined whether or not this is necessary before the 

 deposition of each batch. Judging from analogy, however, it may 

 not be necessary. Hundreds of eggs were obtained in the insectary, 

 but the egg record of one gravid female (Table 1 ) will suffice to show 

 the egg-laying capabilities of the species. This female was placed 

 in a vial with a portion of horse-radish leaf May 1, 1915, and the 

 t-.tal number of eggs laid was 418. 



