insects hover about the infested plants until a larva is seen, when they pounce upon it and carry it away. The eggs of this asparagus beetle are attacked by a minute wasp-like four-winged fly* (Fig. 7) which lays its eggs in those of Fig. 6. THE BORDERED SOLDIER-BUG, an enemy of the common asparagus beetle: a, Adult bug; b, young bug, or nymph. Much enlarged. the beetle, Strangely enough, the parasitized eggs hatch and the larvæ emerging from them become full grown, but are destroyed by the parasite larvæ after the beetle larvæ have entered the soil and formed their pupal cells, but before they have changed to pupæ. Asparagus beetles are very susceptible to sudden changes of temperature and it has been noticed frequently at Concord Mass., that immense numbers of the hibernating beetles are killed in winter during severely cold spells following "open" weather, millions of their dead bodies sometimes being found under bark and in other hiding places. The intense heat that prevailed at times during the summer of 1896, especially during the first two weeks of August, though conducive to the undue propagation of some forms of insects, had the opposite effect upon certain species that feed in the larva condition freely exposed upon the plants. In the vicinity of the District of Columbia this was particularly noticeable in the case of the larvæ of this asparagus beetle. Its eggs, also, seemed to be dried up by the heat. What with the decimation caused by their natural enemies and that caused by the heat, scarcely a beetle or larva was to be found that year after the last of August. Methods of Control Fortunately the common asparagus beetle is not diffi (F. A. Fig. 7. TETRASTICHUS ASPARAGI, a parasite of the com- cult of control and ordinarily may be held in repression by the simplest means. Garden Remedies. Hand picking is of some value in small beds but must of necessity give way to more approved methods for the vast numbers of the beetles that concentrate their forces upon the large areas devoted to this crop in the suburbs of our large cities. • Tetrastichus asparagi Cwid. Chickens and ducks are efficient destroyers of asparagus beetles, and as they do no injury to the plant their services are still in requisition for this purpose at the present day. One of the best remedies against the larvae is fresh, air-slaked lime, dusted on the plants in the early morning while the dew is on. It quickly destroys all the grubs with which it comes in contact. Pyrethrum is credited with being useful, and a mixture of soft soap, quassia decoction, and water (about equal parts of the first two to five of the last) is effective against the larvæ. These remedies, with the exception of air-slaked lime to destroy the larvæ, hardly commend themselves for use on a large scale. Cultural Practices. A practice in high favor among prominent asparagus growers is to cut down all plants, including seedlings and volunteer growth, in early spring, so as to force the parent beetles to deposit their eggs upon new shoots, which are then cut every few days before the eggs have time to hatch for the first new brood. Other measures that have been employed with advantage consist in cutting down the seed stems after the crop has been harvested, and again once or twice during the cutting season, or in permitting a portion of the shoots to grow and serve as lures for the beetles. Here these may be killed with insecticides, or the plants, after they become covered with eggs, may be cut down and burned, and other shoots allowed to grow up as decoys. The trap plants should be destroyed as often as once a week. Naturally when the insects have congregated on the tips early in the cutting season, arsenicals and other substances can not be applied and it is necessary, therefore, to cut as deeply and as often as possible without injuring the product for the market. With concerted action on the part of the growers in following out these methods the insects may be held in check in regions where asparagus does not grow wild in too great profusions; elsewhere insecticides must be used. It is well in any case to employ insecticides after the cutting season, since if the insects are destroyed at this time their numbers the next year will be lessened. The Brushing Method. A simple and inexpensive method of killing the larvæ in hot weather is to beat or brush them from the plants with a stick so that they will drop to the bare ground. The larvæ are delicate creatures, and, as they crawl very slowly, few are able to regain shelter of the plants, but die when exposed to the heated earth. Dusting with Arsenicals. An arsenical, applied dry mixed with flour, as for potato beetles, answers well as an insecticide, destroying beetles as well as grubs, and is of value on plants that are not being cut for food. A mixture of arsenate of lead and air-slaked lime, or plaster, four pounds of the former to a barrel of the latter, is recommended. For satisfactory results the lime and arsenical must be applied at frequent intervals, or as often as the larvæ reappear on the beds. Spraying with Arsenicals. Arsenate of lead has biven better results in spraying than any other arsenical. This insecticide has come into very general use in recent years and has superseded Paris green and other arsenicals for the control of leaf-feeding beetles, such as the potato beetles and asparagus beetles.* It is less harmful * In Pennsylvania a comparative test was made of the value of Paris green and arsenate of lead, showing that not more than 50 per cent of the insects were killed when Paris green and lime were used, while 90 per cent were killed with arsenate of lead; and when resin soap was added to the arsenate of lead to make the latter adhere more closely to the plants, all of the insects were killed on 50 plants treated. In the last experiment the arsenate of lead was used at the rate of 2 pounds to 50 gallons of water, with 5 pounds of resin soap. to growing plants and less likely to burn the leaves, adheres better to the foliage, is less troublesome to prepare, and is more effective. In addition, the spray, on drying, leaves a white coating on the plants, so that it can be readily determined which plants have been treated and which have not. Two pounds of dry lead arsenate, or four pounds of lead-arsenate paste, to fifty gallons of water or Bordeaux mixture will make a solution of sufficient strength to destroy asparagus beetles and their larvæ. The number of sprayings to be applied depends on local and seasonal conditions. Sometimes a single spraying at the proper time will suffice, but occasionally two or three applications are necessary, especially if rainfall intervenes. The adhesiveness of the spray material is promoted by the addition of about the same amount, by weight, of resin-fishoil soap as of the arsenical used. Spraying Apparatus. Extensive experiments have proved that for economy and efficiency the best spraying machinery should be used, even though its initial cost is greater. The "vermorel," "cyclone," and "giant-disk" types of nozzles are the most effective as well as the most economical. When the arsenical is forced through a nozzel of any of these types the spray is mistlike in appearance and adheres to the foliage instead of forming small drops which may roll off. A sprayer of the compressed-air type is the best, the smaller ones being operated by hand and the larger ones by machinery driven by horsepower. THE TWELVE-SPOTTED ASPARAGUS BEETLE A somewhat less injurious species than the preceding is the twelve-spotted asparagus beetle* known to many growers as the red species. It is generally distributed in Europe, where it is apparently native, and, although common, not especially destructive. Like the preceding, it lives exclusively on asparagus, and its chief damage is due to the depredations of the hibernated beetles in early spring upon the young and edible asparagus shoots. Later generations attack the foliage, living, for at least a considerable portion of the larva stage, within the ripening berries. Introduction and Spread in the United States The presence of this insect in America, as has been stated, was first discovered in 1881 in the vicinity of Baltimore, Md. This beetle was noticed in considerable numbers from the first, showing that it had probably been introduced several years earlier. It was then seen only on volunteer asparagus growing on the salty margin of a river, although beds of cultivated asparagus were plentiful in the immediate vicinity. Two years later it had proved even more troublesome than the common asparagus beetle. It has been said of this species that it is one of the most interesting insect pests of which we have knowledge. Its mysterious introduction into the United States, the discovery of its presence in Baltimore, the rapid spread from that center, the keen race northward with the common species, their simultaneous arrival in Canada and progress westward, are only a few of the interesting phases of the history of the twelve-spotted asparagus beetle. Nearly every year since then it has been reported in new localities in the United States and Canada, until now it is well distributed westward and northward. In the Niagara peninsula the two species arrived almost simultaneously, the twelvespotted form being the dominant one. Description, Seasonal History and Habits The mature beetle (Fig. 8, a) rivals the common species in beauty, but may be distinguished by its much broader back and orange-red color. Each wingcover is marked with six black dots, and the knees and a portion of the under * Crioceris duodecimpunctata L. surface of the thorax are marked with black. The beetle, as it occurs on the plant when in fruit, very closely resembles at a little distance a ripening asparagus berry. The common asparagus beetle dodges around a stem like a squirrel when disturbed, but the twelve-spotted form appears to trust to flight, taking wing more readily. Both species make a loud creaking sound, when handled, produced, in the present species, by rubbing the tip of the abdomen against the wing-covers. The full grown larvae (Fig. 8, b) measures, when extended, three-sixteenths of an inch (8 mm.), being of about the same proportions as the larva of the common species, but is readily separable by its orange color The ground color is light yellowish cream with an overlay of yellowish orange which is most pronounced on the outer portions of the abdominal segments. The head, with the exception Fig. 9. Eggs of the twelvespotted asparagus beetle : At left, much enlarged; at right, nearly natural size. of the mouth parts, is also yellowish. The thoracic plate is prominent, divided into two parts, and of a dark-brown color. The second abdominal segments of both species, much enlarged, are shown for comparison at c and d, figure 8. The chief damage inflicted by this species results from the work of the hibernated beetles in early spring upon the young and edible asparagus shoots. Later beetles as well as larvae appear to feed exclusively on the berries. In Europe this species, although common, is not especially destructive. The eggs are deposited singly, and apparently by preference upon old plants, toward the ends of shoots which, lower down, bear ripening berries, and they are attached along their sides (see Fig. 9) instead of at one end, as with the common species. Soon after the larva hatches it finds its way to an asparagus berry, enters it, and feeds upon the pulp. In due time it leaves this berry for another one, and when full grown it deserts its last larval habitation and enters the earth, where it transforms to the pupa and afterward to the beetle. The life cycle does not differ materially from that of the common species, and probably the same number of generations are developed, or nearly as many. Remedies The remedies for the twelve-spotted asparagus beetle are those indicated for the common asparagus beetle, with the possible exception of the caustic lime and some other measures that are directed solely against the larvae of that species, but the habit of the larva of living within the berry places it for that period beyond the reach of insecticides. The collection and destruction of the asparagus berries before ripening might be a solution of the problem, but it is questionable if recourse to this measure would be necessary, save in case of an exceptional abundance of the insect. A thorough spraying with arsenate of lead as advised for the common species should be sufficient for its control. THE GRAPE PHYLLOXERA By Professor J. M. ALDRICH The object of this bulletin is to call the attention of grape growers to the occurrence of the above named enemy of the grape, to describe its mode of attack and the symptoms of its presence, to discuss methods of eradication, and especially to call attention to the great importance of starting new vineyards in such a way as to make them immune to its injuries thereafter. The Grape Phylloxera (Phylloxera vastatrix). While both American and European grapes are affected, the Phylloxera works in its worst form almost entirely on the latter. The American grapes are affected mainly on the leaf, producing small galls or swellings of the tissue. These are very easily noticed. At the same time it occurs to some extent on the roots of the same vines, but does not in most varieties actually kill the roots; most American varieties withstand the root attack so well that no serious effect is produced. In the European varieties the leaf is not attacked, but the insect produces a much worse effect on the roots, multiplying excessively and causing the larger roots to rot. Smaller roots often show galls or swellings, on the surface of which the insects are found. It is much more difficult for the grower to recognize the cause of the trouble in this class of grapes, as there is no appearance of the insect above ground. The main symptom is a weakened vitality, small growth, stunted leaves and fruit, and in two or three years the complete death of the vine. Growers of the European varieties should observe their vineyards carefully, and on the appearance of these indications should seek the assistance of the local horticultural inspector, or send samples of roots from suspected vines to the experiment station for examination To postpone action is the worst possible course to pursue. Phylloxera is a native American insect. Prior to the settlement of the eastern United States, it occurred on the wild vines of that section. In the course of time the introduction of European varieties gave it more favorable conditions, and ultimately it was introduced on grape roots into France and other regions where the European varieties were extensively raised. It is unnecessary to describe the havoc it produced, especially in France and California. Thousands of acres of otherwise magnificent vineyards were destroyed. It is said that in considerable parts of France the principal fuel was stumps of grapevines that had been dug up. The insect is a very small yellow louse, wingless except as hereinafter mentioned. It winters in a half grown condition, and produces eggs in the warmer part of the year. These eggs hatch into forms resembling the adult, and soon grow to maturity. The increase in one season is very great. In vineyards of the European varieties, only the root form occurs, and the spread from vine to vine is comparatively slow, being made under ground. It is estimated at about three rows of vines a year. Under favorable conditions there is produced in some years a winged form, which comes out of the ground and flies away, thus spreading the infestation much more rapidly. The conditions determining the occurrence of a winged brood are not understood. In the eastern states it seems to be an annual occurrence, but in California it is not thought to occur so often; in fact, Professor Woodworth, entomologist of the California Experiment Station, thinks it does not appear oftener than once in ten years on the average, though there is no regular interval. In Idaho no winged brood has as yet been found at all, although the spread which occurred in Juliaette prior to the discovery of the insect can hardly be accounted for on any other theory than the existence of the winged form. |