The Louse

"Better Known than Trusted"

Another "little busie Creature"

Robert Hooke's Louse

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robert hooke's drawing of a louse

Robert Hooke, Micrographia (1665), Courtesy Missouri Botanical Garden

Plate XXXV. Original length of Hooke's enlargement, 342.9 mm (13.5 in).

Possibly a female of the species identified by Carl Linnæus in 1758 as Pediculus humanus. Body length of average live specimen, less than 5 mm (0.196 in)

"This is a Creature so officious," wrote the pioneer English microscopist Robert Hooke, "that 'twill be known to every one at one time or other, so busie, and so impudent, that it will be intruding it self in every ones company, and so proud and aspiring withall, that it fears not to trample on the best, and affects [is drawn to] nothing so much as a Crown." Indeed, Hooke observed from the louse's perspective, it feeds and lives very high, and that makes it so saucy, as to pull any one by the ears that comes in its way, and will never be quiet till it has drawn blood: it is troubled at nothing so much as at a man that scratches his head, as knowing that man is plotting and contriving some mischief against it, and that makes it oftentime sculk into some meaner and lower place, and run behind a mans back, though it go very much against the hair; which ill conditions of it having made it better known than trusted, would exempt me from making ay further description of it, did not my faithful Mercury, my Microscope, bring me other information of it."1

Robert Hooke chose to exhibit his specimen on its back, in order to show some details not visible from above. He began his commentary with the observation that a louse is "a Creature of a very odd shape." It has a head, he wrote, which seems "almost Conical, but is a little flattened on the upper and under sides." Indeed, wrote Hooke, its official "diagnosis"—a biological scientist's taxonomic synonym for "description"—begins with the statement that it is "dorso-ventrally" (back-to-belly) flattened.2 In fact, just as a flea is rarely photographed from overhead or beneath, a louse is rarely pictured from either side, and for the same reason: Those, respectively, are neither informative nor interesting views of either subject.

Immediately behind the widest part of the head are its two black shining goggle eyes BB, looking backwards and fenced round with several small cilia or hairs that incompass it, so that it seems this Creature has no very good foresight: It does not seem to have any eye-lids, and therefore perhaps its eyes were so placed, that it might the better cleanse them with its fore-legs; and perhaps this may be the reason, why they so much avoid and run from the light behind them, for being made to live in the shady and dark recesses of the hair, and thence probably their eye having a great aperture, the open and clear light, especially that of the Sun, must needs very much offend them; to secure these eyes from receiving any injury from the hairs through which it passes, it has two horns that grow before it, in the place where one would have thought the eyes should be; each of these CC hath four joynts, which are fringed, as 'twere, with small bristles, from which to the tip of its snout D, the head seems very round and tapering, ending in a very sharp nose D, which seems to have a small hole, and to be the passage through which [s]he sucks the blood.

Now whereas . . . it seems in several Positions to have a resemblance of chaps, or jaws, . . . yet in other postures those dark strokes disappear; and having kept several of them in a box for two or three dayes, so that for all that time they had nothing to feed on, I found, upon letting one creep on my hand, that it immediately fell to sucking, and did neither seem to thrust its nose very deep into the skin, nor to open any kind of mouth, but I could plainly perceive a small current of blood, which came directly from its snout, and past into its belly; . . . It did not seem at all, . . . to thrust more of its nose into the skin [of the palm of Hooke's own hand], then the very snout D, nor did it cause the least discernable pain, . . . the length of the nose being not more than a three hundredth part of an inch.

At the end of each leg it has two claws, very properly adapted for its peculiar use; . . . by means of the small joynts of the longer claw it can bend it round, and so with both claws take hold of a hair, . . . the long transparent Cylinder FFF, being a Man's hair held by it.

Befriend a Louse Today

Just as every flea bears the onus of potentially becoming—unwittingly of course—a vector of the once-dreaded bubonic plague, so the louse suffers a stigma as the innocent carrier of deadly epidemic typhus, Rickettsia prowazekii (rik-KET-tsee-uh pro-uh-ZEEK-ih-ee. In a spirit closely akin to that of Robert Hooke, the American bacteriologist and immunologist Hans Zinsser (1878-1940), in his book Rats, Lice and History (1935), viewed louse and man in an absurd, if humanely empathetic, relationship:

The louse shares with us the misfortune of being prey to the typhus virus. If lice can dread, the nightmare of their lives is the fear of someday inhabiting an infected rat or human being. For the host may survive; but the ill-starred louse that sticks his haustellum [extremity of the proboscis that functions as a sucking organ] through an infected skin, and imbibes the loathsome virus with his nourishment, is doomed beyond succor. In eight days he sickens, in ten days he is in extremis, on the eleventh or twelfth his tiny body turns red with blood extravasated from his bowel, and he gives up his little ghost. Man is too prone to look on all nature through egocentric eyes. To the louse, we are the dreaded emissaries of death. He leads a relatively harmless life—the result of centuries of adaptations; then, out of the blue, an epidemic occurs; his host sickens, and the only world he has ever known becomes pestilential and deadly; and, as if a result of circumstances not under his control, his stricken body is transferred to another host whom he in turn infects. He does so without guile, from the uncontrollable need for nourishment, with death already in his own entrails. If only for his fellowship with us in suffering, he should command a degree of sympathetic consideration.3

Tsk, tsk! Poor louse!

  • 1. Robert Hooke, Micrographia: Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries Thereupon (London: Jo. Martyn and Ja. Allestry, 1665), Observation 54, "Of a Louse."
  • 2. Ross H. Arnett, Jr., American Insects: A Handbook of the Insects of America North of Mexico, 2nd ed. (Boca Raton, Florida: CRC Press, 2000), 235.
  • 3. Hans Zinsser, Rats, Lice and History, (Boston: Little, Brown and Co.,1935), 168.