INSECT ENEMIES OF EASTERN FORESTS 151 
ern white, red, Scotch, lodgepole, ponderosa, Austrian, and mugho. 
This scale is about 3 mm. long, elongate, and nearly white (fig. 37). 
Male scales awe pure white, narrow, and about one-third as long | as the 
females. 
Uncontrolled infestations of this scale gradually kill branches and 
entire trees. Earlier effects are a yellowing or spotting of needles 
from the insects’ feeding, resulting in a whitish appearance of in- 
tested plants. For control, see p. 3 36. Inthe Eastern States a closely 
allied species, Phenacaspis heterophyllae (Cooley), may be found 
associated with P. pinifoliae on pine, although it apparently is not 
found on spruce. 
The willow scurfy scale (Chionaspis salicis-nigrae (Walsh) ) large 
and pear-shaped, may be encountered on willow and on dogwood, 
serviceberry, yellow poplar, and Cascara buckthorn in the Northern 
States. However, even though it may kill twigs and branches when 
abundant, it seldom kills trees. 
Throughout the United States and southern Canada, in parks or 
other ornamental plantings, the juniper scale (Diaspis carueli Targ.) 
may be found on various species of Juniper, arborvitae, and cypress. 
It is about 2 mm. in diameter, nearly circular, and in color ranges 
from hght gray to white. Although it may become important in 
parks and ornamental plantings it seldom injures forest stands. 
One of the commonest scale insects on ornamentals and hardwood- 
forest growth is the oystershell scale (Lepidosaphes ulmi (1.)). 
The mature female is rather small, 2 to 3 mm. long, narrow anteriorly, 
and broad and rounded posteriorly. Ordinarily the scale is strongly 
curved, but when crowded it may be considerably distorted. In color 
the female ranges from dark brown in summer to grayish in winter 
(Quaintance and Sasscer, 359). 
This species occurs throughout the United States, although it is 
most prevalent and injurious in New England and the Lake States. 
The forest trees most commonly injured are white ash, black ash, 
beech, eastern cottonwood, willow, elm, birch, and maple. The over- 
wintering egos hatch from late in May until late in June, depending 
on the season. This generation matures and lays its eggs in August 
or September in the Northern States, where there ustially 1s one gen- 
eration each year. 
Since Lepidosaphes ulmi is so small and its coloring is such as to 
cause it to blend well with the bark, infestations often pass unnoticed 
until a retardation of branch and twig growth causes an early yel- 
lowing of foliage, and sometimes the death of such growth. It often 
happens that large branches of ash, poplar, and maple trees are killed 
back from the tips by this insect. Ash reproduction is often seriously 
affected, and entire stands of ash have been killed in Ohio. 
The oysterhell scale spreads slowly from tree to tree, since spread 
must take place during the time when first-instar nymphs are crawling. 
This occupies but a few days ys; and therefore most of the scales do not 
escape to other hosts and heavy infestations are permitted to build up 
ona tree. This insect is subject to parasitization by several species of 
hymenopterons and to predatism by birds, mites, and certain insects. 
These controlling influences aid in holding infestations within bounds. 
Where it is thought necessary to apply artificial-control measures, 
good results can be obtained by applying a contact insecticide (p. 53, 
formula 5) just after the eggs hatch. 
