68 INSECTS INJURIOUS TO VEGETATION. 



crescence of a cherry-tree, and from this circumstance named it 

 RhyncluEnas Cerasi^ thecheiry-weevil. The plum, still more than 

 the cherry tree, is subject to a disease of the small limbs, which 

 shows itself in the form of large irregular warts, of a black color, as 

 if charred. Grubs, apparently the same as those that are found in 

 plums, have often been detected in these warts, which arejnow gen- 

 erally supposed to be produced by the punctures of the beetles, and 

 the residence of the grubs. Professor Peck says that " the seat 

 of the disease is in the bark. The sap is diverted from its regular 

 course, and is absorbed entirely by the bark, which is very much 

 increased in thickness ; the cuticle bursts, the swelling becomes 

 irregular, and is formed into black lumps, with a cracked, uneven, 

 granulated surface. The wood, besides being deprived of its 

 nutriment, is very much compressed, and the branch above the 

 tumor perishes."* The grubs found by Professor Peck in the 

 tumors of the cherry-tree, went into the ground on the sixth of 

 July, and on the thirtieth of the same month, or twenty-four days 

 from their leaving the bark, the perfect insects began to rise, and 

 were soon ready to deposit their eggs in healthy branches. 



In order to account for the occurrence of these insects both in 

 the fruit and in the branches of the trees, I have ventured, on an- 

 other occasion, to give the following explanation, although it rests 

 only upon conjecture. The final transformation of the grubs, liv- 

 ing in the fruit, appears to take place at various times during the lat- 

 ter part of summer and the beginning of autumn, when the weevil, 

 finding no young fruit, is probably obliged to lay its eggs in the 

 small branches. The larvae or grubs from these eggs live in the 

 branches during the winter, and are not perfected till near the last 

 of the following June. Should the fall of the fruit occur late in 

 the autumn, the development of the beetles will be retarded till 

 the next spring ; and -this I suppose to be the origin of the brood 

 which stings the fruit. These suggestions seem to receive some 

 confirmation from the known habits of the copper-colored plum- 

 weevils of Europe, which, " in default of plums, make use of the 

 soft spring shoots of the plum and apricot trees."! In cases like 



* See Professor Peck's account of Insects which affect Oaks and Cherry trees; 

 with a plate ; in the " Massachusetts Agricultural Repository and Journal." Vol. 

 V. p. 312. 



t Kollar's Treatise, p. 238. 



