APPENDIX. o4o 



11, certaintj-. However, this is not of as much importance as the fact that the 

 adult beetles all perish in the fall, the winter being passed by the larval 

 stage within the infested trees ; and this, no doubt, is the key to the 

 situation of successfully combating this pest. 



REMEDIES. 



The fruit-tree bark-beetle is attacked in its larval form while within the 

 infested tree by a number of small hymenopterous parasites, perhaps the 

 most common of which is Chiropachijs colon, represented much enlarged in 

 Fig. 4. These insects are capable of doing considerable good in holding the 

 beetles in check, but our experience has been that they are not yet numerous 

 enough in Missouri to materially lessen the damage from the borers. They 

 may some day, however, multiply so as to hold the bark beetle in check. 



While all fruit-tree borers are difficult insects to combat, the fruit-tree 

 bark-beetle is by far the most troublesome, owing to the fact that it is so 

 small and occurs in such large numbers, while it deposits its eggs practically 

 all summer and infests all parts of the tree above ground except the leaves 

 and fruit. 



From the habits of the insect one can readily see that the most essential 

 thing to be done is to keep the trees in a perfectly healthy and vigoi-ous 

 condition, and free fi-om any injury or weakness, or from injured, weakened. 

 or dying parts. This can be done by careful cultivation and fertilization. 

 and by clean culture. Although this pest will infest perfectly healthy trees, 

 it is so much more liable to attack weakened or dying trees that it becomes 

 important that clean culture be practiced, at least insofar as to remove 

 from the orchard and to burn all dead and dying trees or portions of trees. 

 The sooner this can be done the better. If for any season it has not been done 

 during the sunimer it must be done during the winter, and all such trees 

 and limbs burned before March, thereby destroying the insects before they 

 emerge. When a tree or portion of a tree is seen to be dying it is useless to 

 try and save it, and it should be removed and burned at once. Of course a 

 fruitgrower must use his own judgment in discriminating between those 

 that will recover and those that will not; but it is safe to say that if it be 

 attacked to any considerable extent by this pest it is better to remove and 

 burn it. 



Mechanical barriers, such as wrappers, are of little value in preventing- 

 the attack of this insect, except to keep them away from the trunk, and, 

 perhaps, the large limbs ; and on this account it is better to rely upon some 

 wash that can be aplied over a larger part of the tree. 



We have used a wash made by dissolving one pound of potash whale-oil 

 soap in two gallons of water, and applied about the middle of March by 

 means of a spray-pump, and again about the first of April, and have observed 

 good results in repelling the attack of this beetle as long- as the rains allowed 

 the soap to remain on the trees to any considerable extent ; but this spray 

 is too strong to be used when the trees begin to leave out, and on that 

 account it is better to use other washes. 



While we have used, with more or less success, a number of different 



