insect standpoint may be seen at a glance the same trees have been 

 rearranged in a separate table as follows: 



Variety of tree. 



Gingko (Ginyko biloba) 



Tulip tree (Liriodendron tulipifcra) 



Sugar maple (Acer Saccharum) 



1 Red oak (Quercus rubra) 



Tree of heaven (Ailanthus glandulosa) . . 



1 Scarlet oak ( Quercus coccinea) 



Yellow oak ( Quercus velutina) 



Willow oak ( Quercus phellos) 



Black maple (Acer nigrum) 



Japanese sopbora (Sophora japonica) . . . 

 Horse-chestnut (^Esculus hippocasta- 



num) 



Bed maple (Acer rubrum) 



Small-leafed linden (Tilia microphylla) . 



White oak (Quercus alba) 



Sweet gum (Liquidambar styraciflua).. 



Bur oak ( Quercus macrocarpa) 



Kentucky coffee tree (Gymnocladus 



diviaus) 



Sycamore maple (Acer pseudo-plalanus) . 



Insect 

 rating. 



3.0 

 3.0 

 2.5 

 2.5 

 2.5 

 2.5 

 2.5 

 2.5 

 2.5 

 2.5 



2.0 

 2.0 

 2.0 

 2.0 

 2.0 

 2.0 



2.0 

 2.0 



Variety of tree. 



Shingle oak ( Quercus imbricaria) 



Slippery elm ( Ulmus pubesccns) 



Norway maple (Acer platanoides) 



Hardy catalpa (Catalpa tpeciosa) 



European linden (Tilia vulgaris) 



American elm ( Ulmus americana) 



Hackberry ( Celtis occidentalis) 



Silver-leafed maple (Acer saccharinum) 

 Oriental plane tree (Platanus orientalis) 

 American plane tree (Platanus occi- 



dentalitt) 



American linden (Tilia americana) 



Honey locust (Gleditschia triacanthos) . 



Scotch elm ( Ulmus montana) 



Cottonwood (Populus monilifera) 



Balm of Gilead (Populus balsamifera v. 



candicans) 



European elm ( Ulmus campestris) 



Black locust (Robinia pseudacacia) 



Box elder (Negundo negundo) 



Insect 

 rating. 



2.0 



2.0 



2.0 



2.0 



1.5 



1.5 



.5 



.5 



.5 



1 This estimate of the red oak and scarlet oak was based largely on the beautiful 

 condition of certain trees growing in the streets of Washington, D. C. Since the 

 publication of the Yearbook article, however, several of these trees have developed 

 rather serious cases of insect injury. The locust borer (Xyleutes robinice) has attacked 

 a number of the trees, and although it is not apparently weakening their vitality to 

 any serious extent, still it bids fair to do considerable damage. The trees have been 

 treated by injecting a small quantity of bisulphide of carbon into the burrows and 

 covering the opening with putty. In a few cases the obscure scale (Aspidiotus 

 obxcurus) has attacked these trees. It has not as yet killed any branches, but it 

 multiplies as abundantly as its dangerous relative, A. tenebricosus, of the maple, and 

 I see no reason why it should not be an equally injurious species. This experience 

 somewhat shakes the confidence of the writer in his estimate of the rating of these 

 oaks, but not to any very serious extent. 



It will be noticed that the trees listed by Mr. Feruow which we find 

 to be most immune are the gingko and the tulip tree. Outside of the 

 grounds of the Department of Agriculture at Washington and Cen- 

 tral Park, New York, few gingko trees are grown in this country, 

 except as occasional isolated examples. The tree itself is a very 

 beautiful one, and singularly free from insect attack. In the long 

 double row of these trees, now nearly twenty-five years old, on the 

 grounds of the Department of Agriculture, but one species of injuri- 

 ous insect has ever been found, and the work of this species is very 

 insignificant. It is the little sulphur-yellow leaf roller, Tortrix sul- 

 phur tana. 



The tulip tree, which is given the same rating, is, for practical pur- 

 ses, almost as exempt as the gingko. Of late years in the District 



