2. Apple Maggot.—It is fortunate that the apple maggot, often called the railroad worm because of its winding tunnels all through the fruit, is not as serious a pest as the codling moth for it is much more difficult to control with a poison. A two-winged fly appears in early summer and deposits her eggs in a puncture of the skin of the apple. In a few days the eggs hatch and the maggots begin to burrow indiscriminately through the fruit. The full grown larvae are a greenish white in color and about a quarter of an inch long. From the fruit this insect goes to the ground where the pupal stage is passed in the soil. The next summer the fly again emerges and lays its eggs.
Spraying is not effective against this insect as the poison cannot be placed where it will be eaten by the maggots. The best known remedy is to destroy the fruit which drops to the ground and for this purpose hogs in the orchard are very effective. The distribution of this insect in the orchard is limited and it has shown a marked preference for summer and autumn varieties.
3. The Bud Moth closely resembles the codling moth in form and size, but differs from it in color and life history. The larvae, after hibernating through the winter, appear as little brown caterpillars about May first or as soon as the buds begin to open, and a week or two later begin their work of destruction. They inflict great damage on the young leaf and fruit buds by feeding on them. When full grown the larvae, cinnamon brown in color with a shining black head, are about one-half inch long. They then roll themselves up in a tube made from a leaf or parts of leaves securely fastened together with silken threads. In this cocoon pupation, which lasts about ten days, takes place. Early in June the moths appear. There is but one brood in the North. These insects can be successfully combated with a poison spray applied early before the buds open.
4. The Cigar Case Bearer winters in its case attached to a twig. When the buds begin to open in the spring it moves to them, carrying its case with it, and begins to feed on the young and tender buds. By the time the leaves are well open, it has fed a good deal on the tender buds and young leaves and is ready to make a new and larger case. This it does by cutting a leaf to suit and then rolling it up in the form of a cigar, whence its name. In this case the larvae continue feeding about a month, causing much injury to the leaves, although this is not as serious as the mutilation of the young buds in the spring, before the tree is fully leafed out.
About the last of June pupation takes place and in about ten days the moth emerges. The eggs are then layed along the midribs of the leaves and hatch in about fifteen days. The newly hatched larvae become leaf miners during August, and migrate to the branches again in the fall where they pass the winter. These leaf and bud eating insects can be destroyed by applying a poison to the buds before they open and again later to the opening leaf and flower buds.
5. Curculio Beetles pass the winter under leaves and grass. In the spring they feed on the blossoms and the tender leaves. As soon as the young fruits are formed the female deposits her eggs in a puncture made just inside a short, crescent-shaped cut in the little apple. The eggs soon hatch and the young grubs burrow into the fruit to the core where they remain two or three weeks, or until full grown. The larvae then bore their way out of the fruit and drop to the soil where they pupate. The earliest of the beetles to emerge again feed on the fruit. The principal damage from this pest comes from the feeding of the beetles and the work of the larvae, although the latter is not as bad in the apple as in the stone fruits. A poison on the young foliage as soon as the beetles begin to feed is the best method of combating curculio. Jarring the tree is not as practicable with the apple as it is with the plum.
6. The San José Scale, one of our worst apple tree pests, is a sucking insect extracting the juices of the tree from the trunk, limbs or branches, or even from the leaves and fruit when it is very abundant. At first the growth is checked only, but as the insects develop their work finally results in the death of the part, unless they are destroyed. The insect winters in an immature condition on the bark under a grayish, circular, somewhat convex scale about the size of a pinhead. The young, of which a great many broods are produced, are soft bodied but soon form a scale. In the early spring small two-winged insects issue from these scales.
After mating the males die, but the females continue to grow and in about a month begin the production of living young—minute, yellow, oval creatures. These young settle on the bark and push their slender beaks into the plant from which they begin to suck out the sap. In about twelve days the insects molt and in eight to ten more they change to pupae, and in from thirty-three to forty days are themselves bearing young. A single female may give birth to four hundred young in one season and there are several generations in a season. This great prolificacy is what makes the scale so serious a pest.
In fighting it every scale must be destroyed or thousands more are soon born. In order to be able to use a strong enough mixture of lime and sulphur to destroy them by smothering or choking the spray must be applied on the dormant wood in the spring or fall or both. Thoroughness is most essential.
7. The Oyster Shell Scale, although it is essentially the same in its habits and in its methods of sucking the sap from the tree is not as bad a pest as the San José scale because it is less prolific, there being but one brood a year. Still this scale often destroys a branch and sometimes a whole tree. The "lice" winter as eggs under the scale and hatch in late May or early June. After crawling about the bark for two or three days, the young fix their beaks into it and remain fastened there for life, sucking out the sap. By the end of the season they have matured and secreted a scaly covering under which their eggs for the next season's crop winter. A smothering spray like lime and sulphur applied strong when the trees are dormant will practically control this scale. But the young may be destroyed in summer by a contact spray such as tobacco leaf extract or whale oil soap.