55 
The larvse hatch in June, and possibly also in July, from eggs 
laid in crevices in the rougher places of the bark. They bore 
thru the bark at once and begin to mine in the sapwood, some- 
times dipping inward to the older wood or even penetrating to the 
center of a small branch. The irregular mine is always packed with 
the castings of the grub, and increases in diameter, of course, as 
the latter grows, measuring at the largest about an eighth of an inch 
across. Here the borer lives in the larval state until the latter part 
of the following April or early May, when it begins to transform 
within its burrow to the pupa stage, and within another month to 
the beetle. This escapes from the tree from the middle to the last 
of June in northern Illinois, by gnawiiig through the bark, flies 
abroad to feed on the leaves of trees, and soon pairs and lays its 
eggs. Curiously, it seems to feed but little on the birch, preferring 
the leaves of poplar, willow, and elm to those of its native tree. 
There is, indeed, some evidence that it infests the willow, producing 
gall-like swellings on the twigs, but the identity of the species to 
which this injury is referred is not positively settled. 
Trees of large size are often killed by this borer within three or 
four years after they first become infested, and few live more than 
two or three years after the top branches begin to die. The neces- 
sity of prompt action is thus manifest, and as the time of the escape 
of the beetles varies with latitude and the weather of the year, it is 
best to take time by the forelock and to destroy the infested tree 
as early at least as April i. Then one may be sure that nothing can 
have escaped from it to extend the injury. 
This insect is not now known to range beyond Virginia to the 
south or Illinois to the west, but it very likely occurs wherever 
birches are grown. We have lately found it (1910) outside Chi- 
cago, in Elgin, Rock Island, Moline, and Bloomington, abundant 
enough in all these places to be decidedly injurious to the birches. 
It has been quite fully discussed by Professor M. V. Slingerland in 
Bulletin 234 of the Cornell University Agricultural Experiment 
Station, published in January, igo6, and briefer accounts may be 
found in the report of Dr. E. P. Felt, State Entomologist of New 
York, in "Insects Affecting Park and Woodland Trees" (page 
284), published in 1905 ; in an article by F. H. Chittenden published 
in 1898 in Bulletin 18, new series, of the Division of Entomology, 
U. S. Department of Agriculture; and in a paper on "A Disease 
of the White Birch," by John Larsen, printed by the Michigan 
Academy of Science in its third report (1902). 
The Scurfy Scale 
(Chionaspis fiirfura Fitch) 
The so-called scurfy scale is the commonest of all scale insects 
thruout the state on shade and orchard trees. The female scale 
