6 



toes was then attacked, afterwards one of eggplant, and numerous 

 bugs in various stages were observed sucking the juices of these 

 plants. Unripe fruit of eggplant was especially relished, and ripe 

 pods of okra and beans were also attacked. 



The list of useful plants which this species has been found to 

 damage includes all forms of crucifers or cole crops — cabbage and 

 related plants, kale, collards and cauliflower, turnips, radish, horse- 

 radish, mustard, rape, and the like — -and when these crops have been 

 killed out truck crops of nearly all kinds are attacked, of which egg- 

 plant, asparagus, potatoes, tomatoes, okra, beans, and beets are most 

 affected. Damage is sometimes done to ornamental plants such as 

 roses, sunflowers, and chrysanthemums in flower gardens, and Mr. 

 J. M. Rankin, while an agent of this Bureau at Chico, Cal., in Octo- 

 ber, 1905, reported that this species, after entirely destroying a half- 

 acre plat of cabbage, attacked the other plants in the vicinity, includ- 

 ing nursery plants of citrus, loquat, cherry and plum, squash, egg- 

 plant, " and in fact everything green." The fruit of grapes and 

 late corn has also been attacked. The bugs are very partial to rag- 

 weed (Ambrosia), pigweed (Amarantus), wild lettuce {Lactuca 

 canadensis)^ and lambsquarter (Chenopodium), congregating on all 

 parts of these weeds but appearing to prefer the stems. 



The wild food plants on which the species actually breeds include 

 wild mustard and cresses of different kinds, shepherd's purse, pepper- 

 grass, bitter-cress, rock-cress, and practically all other plants of the 

 mustard family (Crucifera^) as well as some of the closely related 

 caper family (Capparidacea?). 



NATURAL ENEMIES. 



The comparative freedom from the attack of natural enemies 

 which the harlequin cabbage bug enjoys is remarkable, and is due to 

 two causes: First, to the warning type of its coloration — black and red 

 or yellow; and, second, to its distasteful odor and flavor. This latter 

 has been tested frequently. In the writer's experience birds that 

 would attack most common insects would, when offered one of these 

 bugs, either peck at it or look at it askance, or if by chance the}^ ate 

 a bug they did not repeat the dose. 



Nevertheless the insect has one effective natural enemy, a minute 

 parasite, Trissolcas murgantiw Ashm., which develops in the egg. 

 Prof. H. A. Morgan when in Louisiana discovered that out of over 

 a thousand eggs under observation in 1902 neai'ly all were killed 

 by this useful little creature. The eggs are also attacked by Ooen- 

 cyrtus johnsoni How. and have been parasitized artificially by Tiis- 

 solcus podisi Ashm. 



[Cir. 103] 



