Cabbage And Cauliflower Insects

The green caterpillars that eat cabbage leaves and heads hatch from eggs laid by the common white butterfly (Fig. 295). There are several broods every season. If plants are not heading, spray with kerosene emulsion or with Paris green to which the sticker has been added. If heading, apply hellebore.

The cabbage aphides, small mealy plant-lice, are especially troublesome during cool, dry seasons when their natural enemies are less active. Before the plants begin to head, spray with kerosene emulsion diluted with 6 parts of water, or whale-oil soap, 1 lb. in 6 gal of water.

The white maggots that feed on the roots hatch from eggs laid near the plant at the surface of the ground by a small fly somewhat resembling the common house fly. Hollow out the earth slightly around every plant and freely apply carbolic acid emulsion diluted with 30 parts of water. Begin the treatment early, a day or two after the plants are up or the next day after they are set out. Repeat the application every 7 to 10 days until the latter part of May. It has also been found to be practicable to protect the plants by the use of tightly fitting cards cut from tarred paper. (See page 187).

Canker-Warms

These caterpillars are small measuring-worms or loopers that defoliate apple trees in May and June (Fig. 217). The female moths are wingless, and in late fall or early spring crawl up the trunks of the trees to lay their eggs on the branches. Spray thoroughly once or twice, before the blossoms open, with 1 lb. Paris green or 4 lb. arsenate of lead in 100 gal. of water. Repeat the application after the blossoms fall. Prevent the ascent of the wingless females by means of sticky bands or wire-screen traps.

Case-Bearers On Apple

The small caterpillars live in pistol-shaped or cigar-shaped cases, about ¼ in. long. They appear in spring on the opening buds at the same time as the bud-moth and may be controlled by the same means.

Codlin-Moth

The codlin-moth lays the eggs that produce the pinkish caterpillar which causes a large proportion of wormy apples and pears. The minute eggs are laid on both the leaves and on the skin of the fruit. Most of the caterpillars enter the apple at the blossom end. When the petals fall, the calyx is open and this is the time to spray. The calyx soon closes and keeps the poison inside ready for the young caterpillar's first meal. After the calyx has closed, it is too late to spray effectively. The caterpillars become full grown in July and August, leave the fruit, crawl down on the trunk, and there most of them spin cocoons under the loose bark. In most parts of the country there are two broods annually. Immediately after the blossoms fall, spray with 1 lb. Paris green or 4 lb. arsenate of lead in 100 gal. of water. Repeat the application about 3 wk. later. Use burlap bands on trunks, killing all caterpillars under them every ten days from July 1 to August 1, and once later before winter.

Cucurbit (Cucumber, Melon, And Squash) Insects

Yellow, black' striped beetles appear in numbers and attack the plants as soon as they are up. Plant early squashes as a trap-crop around the field. Protect the vines with screens (Fig. 229) until they begin to run, or keep them covered with bordeaux mixture, thus making them distasteful to the beetles.

Squash vines are frequently killed by a white caterpillar that burrows in the stem near the base of the plant. Plant a few early squashes between the rows of the late varieties as a trap-crop. As soon as the early crop is harvested, remove and burn the vines. When the vines are long enough, cover them at the joints with earth in order to develop secondary root systems for the plant in case the main stem is injured.

Dark green plant-lice feed on the under sides of squash leaves, causing them to curl and wither. Spray with kerosene emulsion diluted with 6 parts of water. It is necessary thoroughly to cover the under side of the leaves; the sprayer, therefore, must be fitted with an upturned nozzle. Burn the vines as soon as the crop is harvested and keep down all weeds. Tobacco sprays may be used.

The stink-bug is very troublesome to squashes. The rusty-black adult emerges from hibernation in spring and lays its eggs on the under side of the leaves. The nymphs suck the sap from the leaves and stalks, causing serious injury. Trap the adults under boards in the spring. Examine the leaves for the smooth shining brownish eggs and destroy them. The young nymphs may be killed with kerosene emulsion.

Curculio

The adult curculio of the plum and peach is a small snout-beetle that inserts its eggs under the skin of the fruit and then makes a characteristic crescent-shaped cut beneath it. The grub feeds within the fruit and causes it to drop. When full grown, it enters the ground, changes in late summer to the beetle, which finally goes into hibernation in sheltered places. Spray plums just after blossoms fall with arsenate of lead, 6 to 8 lb. in 100 gal. of water, and repeat the application in about a week. After the fruit has set, jar the trees daily over a sheet or curculio-catcher and destroy the beetles; this is practically the only procedure for peaches, for they cannot be sprayed.

The quince curculio is somewhat larger than that infesting the plum and differs in its life-history. The grubs leave the fruits in the fall and enter the ground, where they hibernate and transform to adults the next May, June, or July, depending on the season. When the adults appear, jar them from the tree on sheets or curculio-catchers and destroy them. To determine when they appear, jar a few trees daily, beginning the latter part of May in New York.

Currant-Worm

In the spring the small green, black-spotted larvae feed on the foliage of currants and gooseberries, beginning their work on the lower leaves. A second brood occurs in early summer. When worms first appear, spray with 1 lb. Paris green or 4 lb. arsenate of lead in 100 gal. of water. Ordinarily the poison should be combined with bordeaux (for leaf-spot).