Both the head and antennae are black. The thorax of the male, which is smaller and shorter than that of the female, has the folds and papillae on its sides much less remarkable; but the greatest difference that is found between the two sexes is, that the male is covered with brown elytra, shagreened and marked with two lines longitudinally. The elytra are longer than the abdomen, and under them lie the wings. The two last rings of the abdomen are not so bright as those of the female, only there appear four luminous points, two upon each of the two last rings.

The insect called glow-worm, and which is frequently met with towards evening, in the month of June, in woods and meadows, is the female belonging to this species. By the shining light which it emits, it attracts the male; a wonderful instance of the divine providence. It is apparent that their shining light depends on a liquor placed at the lower extremity of the insect, which when in motion, the light is more lively and shining, and of a finer green. This light the insect withdraws at pleasure, either by unfolding or contracting itself. As a proof that the light depends on a phosphorous matter, you may crush the animal, which, though dead and bruised, leaves a luminous substance on the hand, that only loses its lustre when dried.

The perfect insect flies about during the evening in autumn, and frequents the grassy plantations of juniper trees.