92 DECIDUOUS FEUIT INSECTS AND INSECTICIDES. 



In all, 43 experiments with remedial and preventive measures were 

 conducted during the summer, results of which are given herein. 

 Field observations in this locality seemed to show that apparently 

 health}' trees are attacked and, although the beetles probably do not 

 form egg burrows in these, the loss of sap from the burrows made by 

 the adults in the bark is sufficient to cause the trees to become very 

 much weakened. 



HISTORY. 



The first published notes on this insect were made by Miss M. H. 

 Morris, about 1849-50. At that time Miss Morris credited Tomk-us 

 Jhninaris as being the cause of "peach yellows,'' and so expressed her 

 belief in several articles published in different magazines of that time, 

 stating that the beetles were quite numerous about peach trees suffer- 

 ing from " peach yellows." These suggestions made by Miss Morris 

 probably led Harris to include the insect in his treatise on "The 

 Insects Injurious to Vegetation," published in 1852, where he briefly 

 describes it under the name Tomicus I'nninaris^ this later being 

 changed to Phloeotrihus liminaris. The following extract gives his 

 description : 



There is another small barkbeetle, the Tomicus liminaris of my catalogue, 

 which has been found in great numbers by Miss Morris under the bark of 

 peach trees affected with the disease called the "yellows" and hence supposed 

 by her to be connected with this malady. I have found it under the bark of a 

 diseased elm, but have nothing more to offer from my own observations con- 

 cerning its history, except that it completes its transformations in August and 

 September. It is of a dai-k-brown color, the thorax all punctured, and the 

 wing covers are marked with deeply punctured furrows and are beset with 

 short hairs. It does not average one-tenth of an inch in length. 



The beetle spoken of above as working in elm bark was later found 

 by Mr. E. A. Schwarz, of this Bureau, to be Hylesinus opacidus Lee, 

 he having examined the specimens used by Harris and named it the 

 elm barkbeetle." (This siDecimen, in Mr. Harris's collection, was 

 called Tomicus liminaris and catalogued as such, as is shown by 

 copies, taken by Doctor Hopkins, of the original notes. )^ 



For many years this insect did not become sufficiently important 

 to demand special study, either of its life history or for the deter- 

 mination of remedial measures. Reference to this species has been 

 made at different times, as in the annual reports of the entomologist 

 of the Canadian experimental farms, and by entomologists in the 



"Attention is here called to Mr. Schwarz's article on p. 149, Vol. I, No. 3, 

 Proceedings of the Entomological Society of Washington (1889), on Hylesinus 

 oijaculus. 



''The genus PUlorotrihus is being revised by Doctor Hopkins, who will dis- 

 cuss the synonymy and other systematic features in a bulletin of the technical 

 series of this Bureau. 



