. The clover root-borer. (Hylastinus obscurus Marsham.). Clover Diseases and pests; Agricultural pests; Hylastinus obscurus. Fig. 2.—The clover root-borer: Larva or grub. Much en- larged. (Author's illustra- tion. ) DESCRIPTION OF THE INSECT. The fully developed insect is a small, dark- brown, hard-bodied beetle, shown enlarged in figure 1. The larva, or grub, shown enlarged in figure 2, is about an eighth of an inch long, dingy white, with honey-yellow head and brown jaws. The pupa (fig. 3) is even smaller than the larva, also dingy white, with two minute spinous projections on the top of the
. The clover root-borer. (Hylastinus obscurus Marsham.). Clover Diseases and pests; Agricultural pests; Hylastinus obscurus. Fig. 2.—The clover root-borer: Larva or grub. Much en- larged. (Author's illustra- tion. ) DESCRIPTION OF THE INSECT. The fully developed insect is a small, dark- brown, hard-bodied beetle, shown enlarged in figure 1. The larva, or grub, shown enlarged in figure 2, is about an eighth of an inch long, dingy white, with honey-yellow head and brown jaws. The pupa (fig. 3) is even smaller than the larva, also dingy white, with two minute spinous projections on the top of the head and two somewhat larger ones at the anal extremity. The eggs are elliptical, white, and minute, yet large enough to be seen with the unaided eye. LIFE HISTORY. In the East there is certainly but one generation annually, though this appears to be long drawn out, and scattering indi- vidual larvae and pupae may be found throughout every month of the year. The finding of eggs as late as Sep- tember 18 has been reported from Mcliigan. As a rule, however, the insects pass the winter in the adult stage (fig. 1) within the roots where they developed. During May they abandon the old roots and seek out fresh plants or fields in which to lay their eggs. The eggs are mostly deposited between the middle of May and June 20. The female gouges out a shallow cavity, more often in the crown of the plant, sometimes at the sides of the root even 2 or 3 inches below the crown, and in this places, singly, but not far separated, about half a dozen pale whitish, elliptical, very minute eggs. These hatch in about a week, and the larvae (fig. 2) for a time [Cir. 119]. Fig. 3.—The clover root - borer: Pupa. Much en- larged. (Au- thor's illustra- tion.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Webster, F. M. (Francis
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