554 Transactions of the Ameuican Institute. 



are generally on twigs of the last years growth, and can readily 

 be discovered before they have progressed far enough to cause the 

 outer bark of the twig to crack open, which generally takes place 

 while the blossoms are on the trees. 



The twig commences swelling for a distance varying from three- 

 quarters to three and a half inches up and down its length, and 

 in the course of a few days, causes the outer bark of the twig to 

 burst open from the internal pressure of the growing mass. 



Upon examination by cutting, it will be found that the old wood 

 of the twig has turned dark colored, or has dark streaks running 

 up and down it for the space of one-third of the length of the now 

 rapidly growing knot. When further advanced, the wood of the 

 knot will cleave ofl" from the old wood of the twig, forming a cavity 

 which afterwards becomes the habitation of the grubs. 



I supposed at first, that as this spot appeared to be the center of 

 the difficulty, and the place from which the knot appeared to 

 develop itself, that if they were caused by insects, I should here find 

 the ova, or egg which formed the grub, but in this I was mistaken. 



After about two weeks from the first appearance of the swell- 

 ings which form the knots, and a week or ten days after they are 

 so far advanced as to crack open, the ova, or egg of the insect, may 

 be discovered by careful examination. The first that I discovered 

 this year was on June 10th. At that time I discovered but two, in 

 examining perhaps twenty knots; perhaps a part of this was owing 

 to my want of skill, or experience in the business. 



When the swelling first bursts open, the pulpy woody substance, 

 of which the young knot is composed, is of a light green color, but 

 turns dark with age, until it becomes nearly black; is rough and 

 irregular in form, and has several little indentations in its surface, 

 which have something of the appearance of having been bitten in, 

 by some small insect. In these little indentations or cavities, the 

 eggs are deposited, only one in a place, and from one to about half 

 a dozen — generally three or four — in a knot. I have never been able 

 to find but seven in any one knot, and that only in one instance. 



The eggs are sometimes in sight but not often, being generally 

 imbedded in the woody substance, a little one side of the indenta- 

 tions, or cavities, above spoken of, and but a very short distance 

 from the outside of the knot, and in such a manner as to make one 

 thmk they have worked themselves in since they were deposited. 



These eggs are very small, and not easily discovered; therefore 

 one must look sharp and be careful, or he will not find them. By 



