16 THE REPORT OF THE No. 19 



The Fruit Tree Bark Beetle {Scaly tus riigulosus). 



In August last (1907), while acting as assistant entomologist in the 

 temporary absence of Dr. Bethune and Mr. Jarvis, I received a letter from Mr. 

 Geo. Olmstead, of Grimsbj-, asking whether I knew of a blight that attacked 

 cherry trees. In response to a request for samples of the affected leaves and 

 twigs, Mr. Olmstead sent me as many as he could put in a large envelope. 

 These were examined for fungus diseases and some were also sent to the 

 Bacteriological Department to be tested for bacteria. No fungus or bacteria 

 were discovered to be present. Accordingly I wrote to Mr. Olmstead and told 

 him that I should be making a tour of the Niagara district in a few weeks to 

 investigate the results of the lime-sulphur wash, and would call and try to 

 discover what was the cause of the injury to his cherry trees. 



On September 23rd, I went to Fruitland and in the course of my regular 

 investigations visited many prominent fruit-growers. I asked each of these 

 whether any of their cherry trees had shown any signs of disease. Most of 

 them said that they had observed the leaves of some at least of their trees 

 withering up and dying, but did not know why. On investigation we found 

 that the trees that had been healthy last year and the early part of this year, 

 but that were now dying, were thickly dotted in most cases with gummy ex- 

 udations, varying from the size of a pea to half an inch or more in diameter. 

 On removing the gum from a number of these places we found clear evidence 

 that some insect had bored a tiny hole through the bark in each case and that 

 it was from these w^ounds that the gum had exuded. On further investigation 

 we found a number of the insects themselves. These I identified as Fruit-tree 

 Bark-beetles (Scolytus rugulosus), Fig. 1. They were about one-tenth of an 

 inch in length, and about one-third that amount in width, were nearly 

 cylindrical in shape and black in color. 



A number of orchards were visited in the following localities : Fruit- 

 land, Winona, Grimsby, Jordan, Vineland, and St. Catharines. In nearly 

 all of these the beetles were found attacking not only dead and diseased trees, 

 but also trees that had been perfectly healthy hitherto. In some orchards 

 nearly half of the cherry trees were severely attacked, in others only 

 a very few trees. 



The attacks were not confined to any one variety of cherry tree, for both 

 sweet and sour varieties were assailed. In one orchard, however, where 

 Montmorency and Richmond trees were side by side, the Richmonds were 

 much injured while the Montmorencies were left untouched 



The only other tree besides the cherry on which I found the beetles were 

 a few plum trees in the St. Catharine's district. Two of these especially were 

 very badly covered with gum and were practically past recovery. 



On examination of the habits of the beetle, it was found that they seemed 

 in most cases to have attacked the dead or weak trees first and to have spread 

 from these to the healthy ones. This, I find, is in accordance with the regular 

 accounts given by different writers on the subject. In their attack upon 

 healthy trees the beetles did not confine themselves to any set order of pro- 

 cedure but apparently were just as likely to assail twigs or small branches as 

 the trunk. 



On the trees where the gummy exudations were, I examined a number of 

 the holes from which the gum had exuded, expecting to find larvae present, 

 but in no case did I find any. It looked as if the attacks were made with the 

 intention of causing the tree to die and thus become a proper place for Qgg 

 laying. Larvae, however, were found in considerable numbers under the bark 

 of dead trees. The surface of the wood in such cases, when the bark had been 



