300 TEANSACTIOKS AND PROCEEDINGS OF THE [Sess. ux. 



interior is found to be entirely covered with a kind of 

 yellow silk spun by the insect. The insect itself is of a 

 bright yellow colour with a reddish head. The motions of 

 the insect which cause the bean to jump have been 

 described by Buchenau, in the " Transactions of the 

 Botanical Society of Bremen," 1873. He found that, if 

 the bean is laid on one of its flat sides, the insect can very 

 easily turn it over so as to lie on the other flat side. It is 

 more difficult to turn the bean so as to lie upon its rounded 

 surface and then back again ; and before the insect can do 

 this it must be considerably warmed, to 80° or 90° F, 

 The motions are most energetic when the bean lies upon a 

 roughish surface — for instance on the earth in a flower pot. 

 In order to watch the motions, Lucas cut a hole in the bean, 

 so as to make a sort of window through which he could 

 look, but the insect immediately spun a curtain over this 

 window ; but by making a second window on the opposite 

 side Lucas was able to see the motions of the insect pretty 

 distinctly. He states that the larva takes hold of its web 

 by its hinder feet, then gives a violent jerk with its head 

 and the forward part of its body ; and the head striking the 

 opposite side causes the bean to move, the nature of the 

 motion depending upon the portion of the bean to which 

 the insect has attached itself. If an actively moving bean 

 is held between the finger and thumb the blows of the 

 insect on the interior can often be distinctly felt — eighteen 

 or twenty in succession. They are generally fifteen or six- 

 teen in a minute, but may be as many as two in a second. 

 It is stated that after the larva is full grown it remains 

 active for about nine months before it becomes a chrysalis, 

 and during this time it seems to have no food whatever. 

 The larva cuts a small round piece out of the curved 

 surface of the bean, and this hangs loosely suspended as a 

 sort of door. When the time comes for the perfect insect 

 to emerge from the chrysalis, it pushes its way through the 

 hole ; and the moth then flies away, leaving the skin of the 

 chrysalis in the hole. It appears that there are several 

 other kinds of plants, whose fruits are similarly occupied by 

 insects and move in a similar way ; for instance, some 

 species of Colliguaja growing in Brazil and Chili. 



The Belgian botanist, Mathias de Lobel, about the 



