COLEOPTERA 



165 



are found on the leaves of the same plants. We have many species, but 

 they resemble one another so closely that it is difficult to separate 

 them. 



The asparagus-beetle, Crioceris aspdragi. — This 

 is a small red, yellow, and black beetle, that gnaws 

 holes in the heads of young asparagus, and lays 

 oval, black eggs upon them. The larvae, which are 

 small, brown, slug-like grubs, also feed upon the 

 young heads in the spring, and later in the season a 

 second brood feed upon the full-grown plant. Figure 

 291 represents a head of asparagus bearing the eggs 

 of this beetle, also a beetle and a larva enlarged. 

 The beetle measures about \ of an inch in length. 



The grape rootworm, Fidia longipes. — This in- 

 sect is the most destructive enemy of the grape 

 occurring east of the Rocky Mountains. The adult 

 is a small grayish-brown beetle, measuring about \ 

 of an inch in length. It feeds on the leaves in July, 

 eating out characteristic chain-like holes. The eggs 

 are laid beneath the loose bark of the vines. On 

 hatching, the larvas drop to the ground and burrow down to the roots, 

 which they destroy, causing the death of the vine, Most of the larvae 

 do not transform till the following spring. 



The Colorado potato-beetle, Leptinotarsa dectrrnlinedta. — A good 

 many insect tramps have come to us from Europe and from the Orient, 

 and appropriated whatever pleased them of our growing crops or stored 

 grain. But two of our worst insect pests have swarmed out on us in 

 hordes from their strongholds in the region of the Rocky 

 Mountains. These are the Rocky Mountain locust and the 

 Colorado potato-beetle (Fig. 292). The latter insect dwelt 

 near the base of the Rocky Mountains, feeding upon the 

 sand-burr (Solanum rostratum), until about the year 1859. 

 At that time it began to be a pest in the potato-fields of the 

 settlers in that region. Having acquired the habit of feeding upon the 

 cultivated potato, it began its eastward march across the continent, 

 spreading from potato patch to potato patch. At first the migration 

 took place at about the rate of fifty miles a year, but later it was more 

 rapid; and in 1874 the insect reached the Atlantic Coast. 



The adult beetles hibernate in the ground; they emerge early in April 

 or May, and lay their eggs on the young potato plants as soon as they 

 appear; both larvae and adult beetles feed on the foliage of the potato. 

 The larvae enter the ground to transform. This pest is usually controlled 

 by the use of Paris green. 



The diabroticas. Several very important pests belong to the genus 

 Diabrotica. They are chiefly greenish-yellow beetles, marked with black 

 stripes or spots. The striped diabrotica, D. vittdta, has two black stripes 

 on each wing-cover. The adult feeds on the leaves of cucumber, squash, 

 and melon; and the larva, which is a slender, worm-like creature, bores 

 in the stems and roots of the same plants. The twelve-spotted diabrotica, 

 D. duodecim punctata, and Diabrotica soror, agree in having six black spots 

 on each wing-cover. The former is very common in the East; the latter 

 occurs on the Pacific Coast, and is the most destructive of all of the 



Fig. 292. 



