YALE AGRICULTURAL LECTURES. 33 



other insect, nor are they a vegetable fungus, but are purely a 

 local disease of the limbs, in which the bark and wood are 

 swollen and changed to a spongy substance, but without any 

 of the juiciness which belongs to young fruit. This disease has 

 some analogy to the cancer in the human body, and its cure is 

 the same, namely, the knife, removing the diseased part totally, 

 a> soon as discovered. 



With Melsheimer, Dr. Fitch believes that the curculio breeds 

 in the bark as well as the fruit of trees, for on a specimen of 

 pear-wood sent him some years ago, his microscope revealed 

 crescent cuts in the bark, like those on young fruit, in which 

 little maggots were lying side by side, ready to eat their way 

 onward when the warmth of spring revived them. 



Within six months D. W. Beadle, of St. Catharine's, C. W., 

 has sent the Doctor a curculio parasite, which is furnished 

 with a bristle-like sting with which it pierces the black knot 

 to where the curculio larva lies, and deposits an egg in the 

 body ol the latter, to hatch and gradually kill it. The late 

 David Thomas, of Union Springs, New York, first recom 

 mended knocking the plum-tree to remove weevils. The rem 

 edy is partial, but not infallible. Mr. A. P. Cumings, of 

 New York, recommends to syringe the trees with a mixture 

 of four gallons lime-water, four gallons tobacco-water, one 

 pound whale-oil soap, and four ounces sulphur. The tobacco 

 and soap in solution Dr. Fitch thinks good, but doubts wheth 

 er the other ingredients add anything to the value of the mix 

 ture. There is much testimony to substantiate the fact that 

 trees, whose limbs project over water, always bear fine crops of 

 plums, the curculio being aware that its young will drown if 

 the fruit drops into the water. 



Another important insect is the apple-tree borer, a long 

 grub which resides under the bark and bores into the solid 

 wood, sometimes below, but usually slightly above the ground, 

 and is two or three years in getting its growth. A few years 

 since, an agent of one of our large nurseries canvassed Wash- 

 2* 



