The Garden Magazine, May, 1920 
185 
ber. Badly infested plants bear only a little foliage on the tips 
of the branches and consequently the appearance of the hedge 
is seriously marred. An infested leaf may contain one or two 
to six or more of the miners. These latter winter in the foliage, 
the small, delicate yellowish flies appearing the latter part of 
.May and depositing eggs in a small slit cut by the blade-like ovi- 
positor. Several sprayings with a contact insecticide, prefer- 
ably the tobacco-soap preparation, at three to five day intervals 
beginning when the first insects appear, is the most practical 
method of controlling this insect. A spray containing four 
pounds of molasses to fifty gallons of water traps and destroys 
many insects if applied when the midges are issuing. 
Rhododendron leaves that show an unsightly brown spotting 
on the under surface in May or June, may later reveal the pres- 
ence of a small insect known as the rhododendron lace bug. 
The little pest passes the winter in eggs deposited mostly beside 
the midrib of the leaves. The young hatch probably early in 
May. Thorough spraying with a tobacco-soap preparation 
as soon as the young become somewhat numerous, making the 
application to the under surface of the foliage, is advised. 
W ILTING or dead Rhododendron shoots, specially if they 
break off easily near the surface of the ground and the 
break shows a series of blackened, closely set, nearly horizontal 
galleries about one-sixteenth of an inch in diameter, are vic- 
tims of the pitted Ambrosia beetle. The stems attacked vary 
from one-half to one-and-one-fourth inches in diameter. Its 
operations appear to be confined to shaded localities where 
there is an abundant mulch. Wilting stems should be care- 
fully cut below the point of injury and burned, and a syste- 
matic removal of weakened plants is probably all that is 
necessary in most cases to prevent serious injury. 
The smooth, whitish, boring caterpillars of the rhododendron 
clear-wing confine their operations largely to stems or branches 
a foot or more above the ground. Related to the very common 
currant borer, and like it can be controlled most effectively by 
I cutting and burning infested bushes during the fall and winter. 
ON CONIFEROUS EVERGREENS 
ARBORVITAE leaves are sometimes tunneled by a small 
A caterpillar known as the arborvitae leaf-miner, the 
terminal sprays turning brown later. Sometimes a considerable 
! proportion of the foliage is affected and the specimen trees are 
rendered unsightly and therefore unsatisfactory. The work 
j of this pest is usually confined to the terminal half-inch of the 
I leaves, here and there. The moths emerge about the middle of 
June. No satisfactory control method is known, though it is 
possible that spraying with a tobacco-soap preparation the last 
I of June, or early in July, would destroy many young caterpillars. 
Junipers of various species are occasionally badly infested 
I by a small, circular, white scale insect. Serious damage rarely 
follows infestation though the insect is frequently sufficiently 
1 numerous to warrant spraying with a contact insecticide 
i such as a nicotine-soap solution applied when the small, yellow- 
| ish young appear, namely in June or early July, 
On the Irish Juniper there is sometimes a reddish-brown, 
I white striped caterpillar about one-fourth of an 
inch long which webs the leaves together. This 
little insect apparently thrives upon the dying and 
dead foliage as well, if not better than upon healthy 
tissues. It should be easily controlled, when its 
numbers warrant treatment, by thorough spraying 
■ with arsenate of lead; or the nicotine-soap prepara- 
tion would doubtless prove effective. 
O CCASIONALLY very destructive to young 
Pines is the European pine-shoot moth, ow- 
I ing to its attacking the buds of the terminal cluster, 
especially the leader. This produces a peculiar 
bend, because the borers feed mostly upon one 
side of a shoot. The result is a somewhat characteristic bay- 
onet or post-horn deformity. The early stages of injury are 
indicated only by a somewhat obscure exudation of pitch, fre- 
quently rather granular, at the base of the buds. On examina- 
tion a brown, black-headed borer about three fourths of an inch 
in length may be found within. Cut and burn affected tips. 
Previously referred to is the spruce-gall aphid, a compara- 
tively new pest easily recognized by the cone-like deformity 
it produces upon Norway Spruce in particular, though some 
other varieties are also infested. Trees are rarely killed by this 
insect, though there may be serious deformation because the 
parts of twigs beyond the galls are very likely to die. Thorough 
spraying in April with a whale-oil soap solution, one pound to 
two gallons of water, has proved a very effective check. 
The Norway Spruce is also affected by an easily overlooked 
insect, namely the spruce-bud scale, or Physokermes. This 
little pest establishes itself at the base of the branchlets, or in a 
whorl of buds; and owing to its shape and size being so nearly 
that of a bud it is not readily detected. The young crawl early 
in July. Like other scale insects this pest withdraws a consid- 
erable amount of sap from the parts of the tree whereon it estab- 
lishes itself and consequently there may be a very sickly, un- 
satisfactory development. There are reasons for believing 
that it has caused much damage heretofore supposed to have 
been the work of the spruce-cone gall louse, especially as it is 
occasionally so numerous that the exuded honeydew attracts 
many insects. Spray with a tobacco-soap combination when 
the small brownish young are numerous, about mid-July. 
The pine-bark aphid is occasionally so abundant on the 
smooth bark of the limbs and trunks of Pines as to cover large 
areas with its white cottony secretion, a development particu- 
larly noticeable on the under side of the limbs. The eggs com- 
mence to hatch early in May, at which time the young emerge 
in large numbers from their protective balls of woolly matter 
and travel actively over the bark. They soon settle down on the 
young twigs. This insect appears to thrive best upon park trees. 
Spray thoroughly with a contact insecticide in May. 
IN THE GREENHOUSE 
C HRYSANTHEMUMS are occasionally very seriously 
infested by the chrysanthemum midge, a small insect 
which produces oblique oval swellings about one-twelfth inch 
long on the leaves and young stems of the plants. When 
abundant this may dwarf the Chrysanthemums so seriously as 
to make them practically worthless. It is a recently estab- 
lished greenhouse pest. The galls occur at an oblique angle to 
the surface of the plant and, when fully developed, are easily 
seen; but when small they appear as slight, nodular swellings 
detected best by allowing the leaf to slip through the loosely 
closed fingers. Breeding is more or less continuous. The best 
method of control is thorough and repeated sprayings with a 
nicotine-soap solution, making the first application when the 
flies begin to issue from the galls, and continuing the treatment 
at three to five day intervals until the insects are destroyed. 
Or fumigation may be used, the' most effective being done 
after midnight since most of the flies emerge very early in 
the morning. Once they are destroyed, it is im- 
portant to avoid reinfestation, specially in the 
purchase of plants or cuttings from other green- 
houses. 
Azaleas in greenhouses are occasionally seri- 
ously injured by small yellowish caterpillars only 
about one-fourth of an inch long when full 
grown. They draw the leaves over with a white 
web and skeletonize a portion of the infolded 
underside. Breeding appears to be more or less 
continuous under greenhouse conditions. Re- 
peated fumigation or spraying with a tobacco 
preparation seems to be the most effective method 
of control. 
