While a number of different insects feed upon the asparagus plant, there are only two species which have so far become extensively distributed and caused serious damage in the United States. Both of these were imported from Europe, and are limited for their food supply to the asparagus plant.
This beetle is by far the most important enemy of the asparagus plant. It was first noticed in this country at Astoria, L. I., now a part of New York City, in 1859, but its actual introduction into that locality occurred about 1856. The injury inflicted by this insect is due to the work of both adults and larvæ upon the tender shoots, which they render unfit for market, early in the season. Later they destroy, by defoliation, growing plants, and are particularly injurious to seedlings, the roots of which are weakened by having their tops devoured. Larvæ, as well as beetles, attack the tenderest portions of the plants, but the latter gnaw with seemingly equal relish the epidermis, or rind, of the stems. The beetles are also accused of gnawing young shoots beneath the surface, causing them to become woody and crooked in growth.
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.
[Illustration: 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.