1210 THE BUTTERFLIES OF NEW ENGLAND. 



face has become undermost ; occasionally also when they are fairly ver- 

 tical. They hatch in a little more than a week. 



Food plants. The caterpillar feeds principally on cabbage, but it also 

 attacks cauliflower, another form of Brassica oleracea, and many other 

 cruciferous plants, especially turnip (Brassica napa), horseradish (Nastur- 

 tium armoracia) and radish (Raphanus) ; it has also been found on mus- 

 tard (Sinapis), gillyflower (Matthiola) and sweet Alyssum (Alyssum 

 maritimum) according to Riley and others, all of which are introduced 

 plants. But besides these it has been found on native cruciferae, such as 

 Nasturtium palustre (Scudder), Barbarea vulgaris (Schwarz) and Cakile 

 americana (Hamilton). Messrs. Bowles, Andrews and others have found 

 it plentifully on mignonette. Reseda odorata, belonging to a neighboring 

 family, and it has many times been reported both in this country and in 

 Europe on Tropaeolum, one of the Geraniaceae ; but as the common name 

 of this plant. Nasturtium, is the botanical name of one of the Cruciferae 

 given above, this needs special verification. Specimens that I reared re- 

 fused to eat a growing plant of shepherd's purse (Capsella) . In Europe it 

 has been found on the following genera of Cruciferae : Brassica, Sinapis, 

 Nasturtium, Hesperis, Matthiola, Cheiranthus, Erysimum, Lepidium and 

 Raphanus. Also, as with us, on Reseda, and, according to Riley, it has 

 even been found on a species of Salix in England. 



Habits of the caterpillar. The young caterpillar eats small patches 

 in the parenchyma of the under side of the leaf, and, after feeding, the ac- 

 tivity of the digestive organs can be seen by the rythmical motion of the 

 clubbed hairs on the sides of the body. Later it feeds in exposed positions, 

 usually on the under surfiice, and devours the whole leaf excepting the 

 harder veins. When the plants are headed, it works its way up from 

 below in disconnected passages, riddling the leaves in every direction and 

 forcing itself towards, though rarely to, the very heart of the plant in search 

 of the tenderest leaves ; its ravages are partially concealed by the nearly 

 untouched outer leaves, and the ejectamenta falling through the numerous 

 passages leave the immediate surroundings of the caterpillar comparatively 

 clean. It is on account of this habit of boring into the heart of cabbages, 

 says Riley, that the French Canadians call it the "ver du coeur" or heart- 

 worm, though the true "verdu coeur" of Europe is the allied Mancipium 

 brassicae, the caterpillar of which is of a more social nature, the eggs being 

 laid in open clusters. The damage done by this caterpillar has been very 

 great, especially in the first years after its introduction, before its parasites 

 began to hold it in check. Mr. Greene of St. Alban's Bay, Vt., writes in 

 1869, "Last year I put out 3000 early cabbage plants ; about the first of 

 September these worms made their appearance ; there would be from ten to 

 fifty on a head and the result was they entirely destroyed the crop ; and not 

 only mine but all throughout the country " The Abbe Provancher estimates 



