February, ’20] 
HOLLISTER: SHADE TREE INSECTS 
143 
President W. C. O’Kane: The next paper is by W. 0. Hollister, 
on “The Distribution of Shade Tree Insects in 1919.” 
DISTRIBUTION OF SHADE TREE INSECTS IN 1919 
By W. O. Hollister, Kent , Ohio 
This subject, the distribution of shade tree insects in 1919, is a very 
broad one for if every shade tree insect which appeared were mentioned 
this discussion would be very lengthy indeed. Only the most impor¬ 
tant pests are considered and the territory covered has rather definite 
limits, covering in a general way the country east of the Mississippi 
River and north of the Mason-Dixon line, but more especially that 
territory around the larger cities of Chicago, Cincinnati, Detroit, 
Cleveland, Pittsburgh, Washington, Philadelphia, New York, Newport 
and Boston. 
The source of information is not entirely first hand. It was secured 
mostly from reports sent in by the experts of the company which I 
represent, men who had the opportunity of coming in personal contact 
not only with shade trees but with the insects themselves. The men 
sending the reports have had some training in entomology and con¬ 
siderable training in the care and preservation of shade trees. Their 
reports, as well as those from gardeners of private estates, were sup¬ 
plemented to a limited extent by reports from state entomologists. 
Twice during the season, the first of July and the first of October, a 
list of about forty insects was sent out with a request for information 
regarding their abundance, and from these reports, totaling about 
one hundred and fifty, this paper is compiled. 
It would be difficult to say just what insect was most abundant or the 
one causing the most injury to shade trees this year. Judging from 
the reports which were received no insect appeared to be especially 
serious. Without question though, the most abundant insect was the 
aphid, and it was everywhere. The fruit grower with his systematic 
spraying and careful attention to his orchard should have no trouble 
in controlling these little pests but the shade trees are usually neglected 
and the aphids run wild. Few trees are immune from their attacks 
and many of our finest shade and ornamentals are hosts of one or 
more species. One very conspicuous aphid was the woolly beech 
leaf aphid, Phyllaphis fagi Linn., on the beeches, especially the copper 
beech, Fagus sylvatica, variety purpurea . The attention of the estate 
owner might have been called to the trouble by the shiny appearance 
of the leaves caused by the honey dew or by the whitened appearance 
of the underside of the leaves. Now it is probably true that with a 
few exceptions no one species of insect will kill a shade tree, still they 
