The common asparagus beetle has very efficient checks in the shape of predaceous insects, which prey upon its larvæ and assist in preventing its undue increase. One of the most active of these predaceous insects is the spotted ladybird (Megilla maculata DeG.), represented in its several stages in the illustration (Fig. 44.) The adult of this beetle is rose-colored, with numerous black spots. The spined soldier-bug (Podisus spinosus Dal.) and the bordered soldier-bug (Stiretrus anchorado Fab.) are also useful as destroyers of asparagus beetle larvæ, which they catch and kill by impaling them upon their long beaks and sucking out their juices. Certain species of wasps and small dragon-flies also prey upon the larvæ. Asparagus beetles are very susceptible to sudden changes of temperature, and immense numbers of hibernating beetles are sometimes killed in winter during severe cold spells following "open" weather.
FIG. 44—SPOTTED LADYBIRD
a, larva; b, empty pupal skin; c, beetle, with enlarged antenna above
Remedies.—The common asparagus beetle, under ordinary circumstances, may be held in restraint by the simplest means. Chickens and ducks are efficient destroyers of the insect, and their services are often brought into requisition for this purpose. A practice that is in high favor among prominent asparagus growers is to cut down all plants, including volunteer growth, in early spring to force the beetles to deposit their eggs upon new shoots, which are then cut every day before the eggs have time to hatch. Another measure of value consists in permitting a portion of the shoots to grow and serve as lures for the beetles. Here they may be killed with insecticides, or the plants, after they become covered with eggs, may be cut down and burned, and other shoots be allowed to grow up as decoys. One of the best and least expensive remedies against the larvæ is fresh air-slacked 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. The lime may be conveniently applied by means of a whisk-broom or a Paris green sifter. Even dry road dust applied in this manner will have a beneficial effect. The special merit of these insecticides is that they can be used without the least danger upon young shoots being cut for market or home use.
Paris green and other arsenites, applied dry in powder, mixed with flour or plaster, or in solution, answer equally well, after cutting has ceased, and possess the advantage of destroying beetles as well as larvæ. One pound of Paris green to a barrel of fine plaster makes a sufficiently strong mixture. It may be necessary to make two of these applications at intervals or as often as the larvæ reappear on the plants. Powdered hellebore mixed with flour, one part to ten, or in solution of one ounce of hellebore to three gallons of water, is also very effective against the young larvæ. Pyrethrum or buhach may be used in similar manner, and kerosene emulsion has been highly recommended by some experimenters. In hot weather, when the soil is dry, the larvæ may be brushed or shaken from the plants so that they will drop to the heated ground, where they die, being unable to regain the shelter of the plants. Whichever methods for the destruction of this pest are adopted, unless the work be done thoroughly and with concerted action by all the growers in the section, the relief can not be permanent.
THE TWELVE-SPOTTED ASPARAGUS BEETLE
(Crioceris 12-punctata Linn)
The presence of this insect in America was first detected in 1881, and it is still much rarer and consequently less injurious than the preceding species. In Europe, where it is apparently native, it is common but not especially destructive. The chief source of damage from this species is from the work of the hibernated beetles in early spring upon the young and edible asparagus shoots. Later beetles as well as larvæ appear to feed exclusively upon the berries. The eggs are deposited singly, and apparently by preference, upon old plants toward the end of shoots, which, lower down, bear ripening berries, and they are attached along their sides instead of at one end, as in the case with the eggs of the common species. Soon after the larva hatches from the egg it finds its way to an asparagus berry, enters it, and feeds upon the pulp. In due time it leaves the first berry for another one, and when full growth is attained it deserts its last larval habitation and enters the earth, where it transforms to pupa and afterward to the adult beetle. The life cycle does not differ materially from that of the common species, and there are probably the same or nearly as many generations developed.
