LEPIDOPTERA. 233 



An expert person will readily detect them by their ravages on 

 the plants which they inhabit; and a few minutes devoted, 

 every day or two, to a careful search in the garden, during the 

 season of their depredations, will suffice to remove them 

 entirely. 



In Europe there are several kinds of caterpillars which live 

 exclusively on the cruciferous or oleraccous plants, such as 

 the cabbage, broccoli, caulillower, kale, radish, turnip, and 

 mustard, and oftentimes do considerable injury to them. The 

 prevailing color of these caterpillars is green, and that of the 

 butterflies produced from them, white. They belong to a 

 genus called Pontia; in which the hind wings are not scol- 

 loped nor tailed, but are rounded and entire on the edges, and 

 are grooved on the inner edge to receive the abdomen ; the 

 feelers are rather slender, but project beyond the head ; and 

 the antennee have a short flattened knob ; their caterpillars are 

 nearly cylindrical, taper a very little towards each end, and 

 are sparingly clothed with short down, which requires a micro- 

 scope to be distinctly seen ; they suspend themselves by the 

 tail and a transverse loop; and their chrysalids are angular at 

 the sides, and pointed at both ends. 



In the northern and western parts of Massachusetts there is 

 a white butterfly, which, in all its states, agrees with the fore- 

 going characters. It is the Pontia oleracea, potherb Pontia, or 

 white butterfly, and was first described by me in the year 

 1829, in the seventh volume of the " New England Farmer."* 

 About the last of May, and the beginning of June, it is seen 

 fluttering over cabbage, radish, and turnip beds, and patches 

 of mustard, for the purpose of depositing its eggs. These are 

 fastened to the under sides of the leaves, and but seldom more 

 than three or four are left upon one leaf. The eggs are yel- 

 lowish, nearly pear-shaped, longitudinally ribbed, and are one 

 fifteenth of an inch in length. They are hatched in a week or 

 ten days after they are laid, and the caterpillars produced from 

 them attain their full size when three weeks old, and then 



* Page 402. For a figure of it, see " Lake Superior," by Agassiz & Cabot, 

 pi. 7, tig 1- 



30 



