242 TRANSACTIONS OF THF. ILLINOIS 



CABBAGE INSECTS. 



(A paper prepared expressly for the Illinois State Horticultural Society, by Cyrus Thomas, State 



Entomologist.) 



Cabbage (^Brassica oleraced) is one of the vegetables brought into 

 use at an early day, and although not indispensable, like the potato, is 

 nevertheless an esculent highly esteemed, and has assumed an importance 

 that gives it a prominent position not only in the horticultural catalogue, 

 but also in estimating the production of our country. I have no statistics 

 by which to estimate its value in this country, but when we learn that in 

 London about one hundred millions heads are annually sold, which at but 

 five cents a head would amount to ^5,000,000, we may be prepared to 

 estimate the amount raised in Illinois at a sum worthy of being taken 

 into consideration in estimating the value of our productions. 



Just when and where it was first brought into use it is not possible to 

 state now with certainty. A comparatively recent article in Hardwicke^ s 

 Science Gossip says that the plant from which the varieties in use in Eng- 

 land originated is to be found along the southeast sea-coast of England. 

 But it is certain that some of the varieties were early in use on the western 

 side of the continent ; also that kale or colewort of some kind was long 

 in use in Greece and Rome, as they are frequently mentioned by Greek 

 and Roman writers, and even directions given for their cultivation. It is 

 also certain that various species of Brassica are found in different parts 

 of the world. 



But it is not my intention at present to enter into the history of this 

 vegetable farther than to call attention to the fact that our species is 

 probably a native of a northern maritime country, although the genus is 

 distributed over the temperate climate of Europe, Asia and Africa. 



Naturally of a succulent character, which has been greatly increased 

 by cultivation, it is thereby rendered more than ordinarily liable to the 

 attacks of leaf-eating insects. 



What were its original insect enemies we have no means now of 

 ascertaining with any certainty; but it is evident that the change made 

 in it by cultivation and its extension over a large portion of the world 

 has added considerably to the list of its insect foes. As the westward 

 extension of the area of potato cultivation has added to the insect ene- 

 mies of this vegetable, in this country, so the western and southern 

 extension of the cultivation of cabbage has increased the number of its 

 foes. We may mention as examples, in proof of this statement, the 

 Southern Cabbage-butterfly {Pieris protodice') and the Harlequin Cabbage- 

 bug {^Murgantia histrionicd). The latter, in fact, did not commence its 

 attack until this vegetable began to be cultivated in a certain portion of 

 the Gulf region. 



As the chief portion of this plant as grown under cultivation consists 

 of its leaves, the attacks of its insect enemies are directed chiefly, and in 

 fact almost entirely, against these. As the leaves constitute the edible 

 portion of the plant, this fact limits the application of topical remedies 

 to such substances as will not endanger life by their poisonous qualities. 



