The beetle illustrated in Fig. 42 is a most beautiful creature—from the entomologist's point of view—slender and graceful in form, blue-black in color, with red thorax and lemon-yellow and dark blue elytra or wing covers, with reddish border. Its length is a trifle less than one-fourth of an inch.
FIG. 42—COMMON ASPARAGUS BEETLE
a, beetle; b, egg; c, newly hatched larva; d, full-grown larva
From the scene of its first colonization in Queen's County, N. Y., the insect migrated to the other truck-growing portions of Long Island. It soon reached southern Connecticut, and has now extended its range northward through Massachusetts to New Hampshire. Southward it has traveled through New Jersey, where it was first noticed in 1868, to southern Virginia. At present it is well established in the principal asparagus-growing sections of New England, of New Jersey, Delaware, and Maryland, and is present in Pennsylvania, New York, and Ohio. The question of distribution is an important one, as this species is rapidly extending its range. In a very few years we may expect its spread to other portions of the States in which it is now local, and later it will naturally move westward to Indiana and other States west and south of there.
The insect passes the winter in the beetle state under convenient shelter, and toward the end of April or early in May, according to locality, or at the season for cutting the asparagus for market, issues from its hibernating quarters and lays its eggs for the first brood. The eggs are deposited endwise upon the stem or foliage, and in the early spring upon the developed stalks, usually in rows of from two to six, or more. In from three to eight days the eggs hatch, the young larvæ, commonly called "grubs" or "worms," presenting the appearance indicated in Fig. 42, c. They at once begin to feed, and are from ten days to a fortnight, according to Fitch and others, in attaining full growth. When full grown the larva appears as in Fig. 42, d. It is soft and fleshy, much wrinkled, and in color dark gray or olive, which usually becomes lighter and yellowish with age. The mature larva enters the earth, and here, within a little rounded, dirt-covered cocoon which it forms, the pupa state is assumed. In from five to eight or more days the adult beetle is produced, which soon issues from the ground in search of food and of a suitable place for the continuance of the species. In Fig. 43 is shown a spray of asparagus, with the common asparagus beetle in its different stages, asparagus top at the right showing eggs and injury.
FIG. 43—SPRAY AND TOP OF ASPARAGUS ATTACKED BY BEETLES
The duration of the life cycle is about thirty days from the time the eggs are laid until the insects attain maturity, but the time is shorter in the hotter parts of a season than in the cooler days of May or September. In the District of Columbia the eggs, in the warmest part of midsummer, develop in three days and the pupæ in five days. From this it may be estimated that, in the very warmest weather, the development of the insect may be effected in about three weeks from the time the egg is laid. In colder climates and in spring and autumn the development from egg to beetle will require from four to perhaps seven weeks. In the northern range of the species, two and perhaps three broods are usually produced, and farther southward there is a possibility of at least a fourth generation. In the latitude of the District of Columbia the beetles usually disappear to enter into hibernation in the latter days of September.