Ampeloglypter sesostris

Ampeloglypter ampelopsis

Colomerus vitis

Contarinia johnsoni

Evoxysoma vitis

Daktulosphaira vitifoliae

Ampeloglypter sesostris Leconte

From Missouri to Ohio and West Virginia grape-canes are sometimes injured to a slight extent by the attacks of a reddish- brown weevil, the larva of which feeding in the cane just above one of the joints produces a swelling or gall from one to one and one half inches in length and about twice the diameter of the cane in thickness. The insect hibernates in the adult state under leaves or other suitable shelter. The weevils emerge from winter quarters in May and the female begins egg-laying as soon as the vines have made sufficient growth. 

For oviposition she usually selects a place directly above the lowest joint which does not bear a fruit cluster. She first bores a hole with her snout in the heart of the cane, deposits an egg in it and then fills the cavity with bits of bark fiber scraped from the surface of the cane. She then makes a row of eight to fourteen similar punctures directly above the first and fills them with fiber, but does not deposit an egg in any except the first. As the gall increases in size this row of punctures produces an ugly wound which does not heal as long as the gall is inhabited. 

The egg hatches in a week or ten days. The larva feeds principally on the pith, working its way up or down the cane for a considerable distance. When full-grown the larva is about two fifths inch in length, yellowish-white in color, with a brownish head and dark brown jaws. It becomes full-grown in eight or ten weeks, pupates within the gall and the beetles emerge in August. 

The injuries caused by this insect are never serious; affected canes, unless broken by the wind, continue to grow and are able to ripen their fruit as well as those not infested. The insect may be killed by cutting out and burning the infested canes during July and early August, but ordinarily it would not be worth the trouble involved. In vineyards sprayed with an arsenical in Bordeaux mixture in late May and June many of the beetles are doubtless poisoned.

Ampeloglypter ater Leconte

This small black weevil is generally distributed throughout the Eastern and Western states, where it usually feeds on Virginia creeper. In West Virginia, however, it has recently attracted attention as a minor enemy of the grape. 

The beetle emerges from hibernation in May and after inserting its egg in a puncture in a growing grape-cane girdles the branch below the egg and then usually eats off the tip of the branch and one or more of the leaves. These withered tips and leaves sometimes give the vine a decidedly ragged appearance, although the actual injury is not great. 

The eggs hatch in about ten days and the white footless grub feeds on the pith, becoming full-grown in July. About this time the infested cane usually breaks off at the first joint below the egg puncture and drops to the ground. Pupation takes place in the cane and the beetles emerge in August. 

Eriophyes vitis Landois

In central Europe, Italy and in California the leaves of the vine are often deformed by attacks of a minute mite. In in- fested leaves the portions between the larger veins puff up, leaving a cavity on the under side which is clothed with a dense felt-like covering. As a rule, thin-leaved varieties of grape are more subject to attack, or at least show greater evidence of the presence of the mite. In California erinose rarely causes serious injury to the vine or to the crop; it has often been confused with a fungous disease, the powdery mildew.

The mite, as usually found on the leaf, is a minute, nearly colorless, elongate, four-legged creature, about .13 mm. in length. The mites hibernate under loose strips of bark on the larger branches of the vine and in the spring migrate to the under side of the opening leaves where they puncture the epidermal cells with their sharp mandibles, thus producing abnormal thread-like outgrowths from the underlying layers of cells, known as erinea. These erinea when abundant have the appearance of dense felt, and it is in the shelter thus afforded that the mites live, lay their eggs and the young find suitable food. From time to time individuals leave the older leaves and start new colonies on the young leaves at the ends of the branches. In the fall some of the mites desert the leaves and go into hibernation on the bark of the older canes.

Contarinia johnsoni Slingerland

This grape pest was first discovered in the Chautauqua grape region of western New York in 1904, and as far as known is still confined to that locality. A closely related species causes a similar injury to grapes in Europe. Its presence in a vineyard is first indicated by abnormally enlarged, yellowish or dark reddish blossom buds (Fig. 378) which fail to open and drop off about the normal time for blossoming. Opening one of these enlarged buds, it will be found to contain a number of small whitish or yellowish maggots from 1/16 to 1/12 inch in length (Fig. 379). From 10 to 60 per cent of the buds are sometimes destroyed, giving the clusters a very thin and ragged appearance, and thus decreasing considerably the market value of the crop. 

The parent insect is a delicate two-winged midge with a yellowish body and straw colored legs (Fig. 380). The inch in length and the male a little smaller. The flies emerge from the ground in the latter part of May just as some of the blossom buds of such early varieties as Moore, Early and Worden begin to show a small opening at the tip caused by a spreading of the petals. The female deposits her minute, grayish, elongate, slightly curved eggs in the interior of the bud by means of an extensile fleshy ovipositor inserted through this opening in the apex of the bud. From a few to seventy maggots may be found in a single bud, but twenty-five is about the average in a year of heavy infestation. The infested buds contain a watery fluid in which the maggots live. Such buds become greatly swollen, often three times as large as normal, and turn yellowish, becoming dark reddish, particularly toward the tip. When full-grown the maggot is about 1/12 inch in length and of a yellowish or orange color. They usually escape by the opening at the apex, fall to the ground, where at a depth of about 6 inches they pass the winter as larvae, curled up in small, ovoid, silken lined, earthen cocoons about 1/25 inch in length. Pupation takes place the last of April and the adults emerge about a month later.

Evoxysoma vitis Saunders

The seeds of the wild grape in the eastern United States and Canada are commonly infested by a milk-white larva about 1/8 of an inch in length which eats out the kernel. The insect passes the winter as a larva within the seed. Pupation takes place in June, and in early July the adult gnaws its way out of the seed, leaving a small, round hole. The adult is a small four-winged fly about 1/8 inch in length and black in color. The female is provided with a sharp needle-like ovipositor which she inserts through the skin and pulp of the grape and deposits her minute whitish egg in the kernel of the seed. Most of the egg-laying takes place in July. Cultivated varieties are rarely infested, but we have occasionally seen Delawares badly injured by the punctures made by the female in ovipositing. The injured berries color prematurely and sometimes shrivel and drop. Infestation by the grape-seed chalcis may be prevented by destroying all wild grape-vines in the vicinity of the vine- yard, and by not allowing any of the infested fruit to remain in the vineyard after picking time. 

Phylloxera vastatrix Planchon

This destructive plant-louse is a native of the eastern United States, where it originally infested the leaves and roots of the various species of wild grapes. Sometime before 1863 it was introduced into the great wine-producing regions of France, and there proved a deadly enemy of the European grape (Vitis vinifera). By 1884 a third of the vineyards of France had been destroyed, and a much larger area had been seriously affected. It was introduced into California some time before 1874 and is now present in most of the grape-producing regions of the state except in the southern part. As most of the grapes grown commercially in California are of the vinifera or European type, the phylloxera has there been one of the most important insect pests with which the vineyardists of the Pacific slope have had to contend. The phylloxera has also been introduced into New Zealand and South Africa, and also occurs in southern Russia and in Algeria. 

The life history of the grape phylloxera is a complicated one. In its destructive form it is a small, yellowish, wingless root- louse about ^ of an inch in length found clustering on the roots of the vine. In feeding, the louse inserts the sharp and slender stylets of the beak and sucks out the sap, thus causing an irritation which produces an abnormal enlargement of the roots known as nodules. These sweUings are yellow in color, soft and watery, and after a time break down and decay, causing the death of the root. The underground forms molt three times before becoming mature ; they are all females and re- produce without being fertilized. The number of eggs laid by a single individual varies considerably with the climate and the season, but rarely exceeds a hundred. The eggs are oval in form, yellow in color and about ^ of an inch in length ; they are laid singly or in clusters on the roots of the vine. 

There may be six generations of the root-inhabiting form annually, and experimental rearing has shown that reproduction may continue in this way for several years without appreciable loss of vigor or of prolificness. Normally, however, during the latter half of the season some of the Uce infesting the roots become more elongate than the others and have longer legs and antennae. These forms do not become mature at the third molt and begin to lay eggs, but continue their development; at the fourth molt, wdng pads become visible on the thorax ; and at the fifth and last molt, which takes place after the nymph has crawled to the surface, functional wings are acquired. After waiting a few hours for the wings to dry and the body to harden, they take flight and, if a wdnd is blowing, may be trans- ported a considerable distance. After feeding about a day on the under side of one of the tender leaves at the end of the shoots they are ready to deposit their yellowish-white eggs of two distinct sizes ; from the larger eggs are developed the true females and from the smaller ones the true males. Both sexes are wingless, and the female after fertilization deposits a single so-called winter egg on the bark of the older canes. These sexual forms are much smaller than the others, and functional mouth parts are lacking. The insect does not pass the A\anter exclusively in the egg state, but many of the younger indi\aduals of the root-inhabiting form, as well as many of the later migrants from the leaves, hibernate in small groups on the larger roots. 

The winter eggs hatch in the spring soon after the first grape leaves have become well expanded, and the young Uce normally crawl up the canes to the leaves, where they settle on the upper surface and begin sucking out the juices of the leaf. The puncture made in feecUng stimulates the growth of the leaf cells so that a hollow gall is formed, projecting from the mider side of the leaf and opening by a narrow slit on the upper surface (Fig. 390). The opening is guarded by a dense growth of do^\^l. Within this cavity the insect continues its develop-ment and becomes mature after the third molt, which occurs in about fifteen days. The forms producing the galls are all wingless females, and each individual of the earUer generation may lay from 500 to 600 eggs during the three weeks of her life as an adult. Towards the end of the season the later broods are not so prolific, 100-200 eggs being the maximum. The eggs hatch in about eight days, and the young escape from the gall by the opening on the upper surface of the leaf and migrate to the tender leaves at the end of the branches, where new galls are formed. From five to seven generations of the gall- inhabiting form occurs annually. Nearly all the young of the earlier generations migrate to the leaves, but after the third generation an increasing number migrate to the roots, where they join their underground sisters in their insidious attack on the vine. 

The complete life history, as outlined above, occurs only when the phylloxera is living on the species of grapes more closely related to its native food-plant. In Europe and in California the leaf galls are rarely seen. Under these circumstances it is supposed that the lice hatching from the so-called winter eggs may migrate at once to the roots. That such is the case, however, does not seem to have been proved by direct observation. 

Manual of fruit insects