PROTECTING PLANTS FROM THINGS THAT PREY ON THEM - Continued
The best time to apply these poisoned baits is two or three days before
any plants have come up or been set out in the garden. If the ground has
been properly prepared, the worms will have had but little to eat for
several days and they will thus seize the first opportunity to appease
their hunger upon the baits, and wholesale destruction will result. The
baits should always be applied at this time wherever cut-worms are
expected. But it is not too late usually to save most of a crop after
the pests have made their presence known by cutting off some of the
plants. Act promptly and use the baits freely.
For mechanical means of protecting from cut-worms, see pp. 186-7.
[Illustration: Fig. 235. Elm-leaf beetle, adult, somewhat enlarged
(after Howard).]
Elm-leaf beetle.--Generally speaking one thorough and timely spraying
is ample to control the elm-leaf beetle (Fig. 235). Use arsenate of
lead, 1 lb. to 25 gal., and make the application to the under side of
the leaves the latter part of May or very early in June in New York.
Occasionally, when the beetle is very abundant, due in all probability
to no spraying in earlier years, it may be advisable to make a second
application, and the same may be true when conditions necessitate the
application earlier than when it will be most efficacious. This latter
condition is likely to obtain wherever a large number of trees must be
treated with inadequate outfit.
Oyster-shell scale.--This is an elongate scale or bark-louse, 1/8 in.
in length, resembling an oyster shell in shape and often incrusting the
bark of apple twigs. It hibernates as minute white eggs under the old
scales. The eggs hatch during the latter part of May or in June, the
date depending on the season. After they hatch, the young may be seen as
tiny whitish lice crawling about on the bark. When these young appear,
spray with kerosene emulsion, diluted with 6 parts of water, or
whale-oil or any good soap, 1 lb. in 4 or 5 gal. of water.
Pear insects.--The psylla is one of the most serious insects
affecting the pear tree. It is a minute, yellowish, flat-bodied, sucking
insect often found in the axils of the leaves and fruit early in the
season. They develop into minute cicada-like jumping-lice. The young
psyllas secrete a large quantity of honey-dew in which a peculiar black
fungus grows, giving the bark a characteristic sooty appearance. There
may be four broods annually and the trees are often seriously injured.
After the blossoms fall, spray with kerosene emulsion, diluted with 6
parts of water, or whale-oil soap, 1 lb. in 4 or 5 gal. of water. Repeat
the application at intervals of 3 to 7 days until the insects are
under control.
The pear slug is a small, slimy, dark green larva which skeletonizes the
leaves in June, and a second brood appears in August. Spray thoroughly
with 1 lb. Paris green, or 4 lb. arsenate of lead, in 100 gal. of water.
Potato insects.--The Colorado potato beetle, or potato-bug, emerges
from hibernation in the spring and lays masses of orange eggs on the
under side of the leaves. The larvae are known as "slugs" and
"soft-shells" and cause most of the injury to the vines. Spray with
Paris green, 2 lb. in 100 gal. of water, or arsenite of soda combined
with bordeaux mixture. It may sometimes be necessary to use a greater
strength of the poison, particularly on the older "slugs."
The small black flea-beetles riddle the leaves with holes and cause the
foliage to die. Bordeaux mixture as applied for potato blight protects
the plants by making them repellent to the beetles.
Raspberry, blackberry, and dewberry insects.--The greenish, spiny
larvae of the saw-fly feed on the tender leaves in spring. Spray with
Paris green or arsenate of lead, or apply hellebore.
The cane-borer is a grub that burrows down through the canes, causing
them to die. In laying her eggs, the adult beetle girdles the tip of the
cane with a ring of punctures, causing it to wither and droop. In
midsummer, cut off and destroy the drooping tips.
Red spider.--Minute reddish mites on the under sides of leaves in
greenhouses and sometimes out of doors in dry weather. Syringe off the
plants with clear water two or three times a week, taking care not to
drench the beds.
Rose insects.--The green plant-lice usually work on the buds, and
the yellow leaf-hoppers feed on the leaves. Spray, whenever necessary,
with kerosene emulsion, diluted with 6 parts of water, or whale-oil or
any good soap, 1 lb. in 5 or 6 gal. of water.
The rose-chafer is often a most pernicious pest on roses, grapes, and
other plants. The ungainly, long-legged, grayish beetles occur in sandy
regions and often swarm into vineyards and destroy the blossoms and
foliage. Spray thoroughly with arsenate of lead, 10 lb. in 100 gal. of
water. Repeat the application if necessary. (See under Rose in
Chap. VIII.)
San José scale.--This pernicious scale is nearly circular in outline
and about the size of a small pin head, with a raised center. When
abundant, it forms a crust on the branches and causes small red spots on
the fruit. It multiplies with marvelous rapidity, there being three or
four broods annually in New York, and each mother scale may give birth
to several hundred young. The young are born alive, and breeding
continues until late autumn when all stages are killed by the cold
weather except the tiny half-grown black scales, many of which hibernate
safely. Spray thoroughly in the fall after the leaves drop, or early in
the spring before growth begins, with lime-sulfur wash, or miscible oil
1 gal. in 10 gal. of water. When badly infested, make two applications,
one in the fall and another in the spring. In case of large old trees,
25 per cent crude oil emulsion should be applied just as the buds
are swelling.
In nurseries, after the trees are dug, fumigate with hydrocyanic acid
gas, using 1 oz. of potassium cyanide for every 100 cu. ft. of space.
Continue the fumigation from one-half to three-quarters of an hour. Do
not fumigate the trees when they are wet, since the presence of moisture
renders them liable to injury.
Tent-caterpillar.--The insect hibernates in the egg stage. The eggs
are glued in ring-like brownish masses around the smaller twigs, where
they may be easily found and destroyed. The caterpillars appear in early
spring, devour the tender leaves, and build unsightly nests on the
smaller branches. This pest is usually controlled by the treatment
recommended for the codlin-moth. Destroy the nests by burning or by
wiping out when small. Often a bad pest on apple trees.
Violet gall-fly.--Violets grown under glass are often greatly injured
by a very small maggot, which causes the edges of the leaves to curl,
turn yellowish, and die. The adult is a very minute fly resembling a
mosquito. Pick off and destroy infested leaves as soon as discovered.
Fumigation is not advised for this insect or for red-spider.
White-fly.--The minute white-flies are common on greenhouse plants and
often in summer on plants about gardens near greenhouses. The nymphs are
small greenish, scale-like insects found on the under side of the
leaves; the adults are minute, white, mealy-winged flies. Spray with
kerosene emulsion or whale-oil soap; or if infesting cucumbers or
tomatoes, fumigate over night with hydrocyanic acid gas, using 1 oz. of
potassium cyanide to each 1000 cu. ft. of space. (See page 188.)
White grubs.--The large curved white grubs that are so troublesome in
lawns and strawberry fields are the larvae of the common June beetles.
They live in the ground, feeding on the roots of grasses and weeds. Dig
out grubs from beneath infested plants. Thorough early fall cultivation
of land intended for strawberries will destroy many of the pupae. In
lawns, remove the sod, destroy the grubs, and make new sward, when the
infestation is bad.
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