The Swelling and the Itch

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Topical Summary: Six species in four stories—Linnæus in English—A swarm of names—The -ologies of it—Metamorphosis—Swammerdam's closeup—Lip service—Love song—Poets and philosophers—"Murmuring small trompets"—Fighting back—Social swarm—"Intermittent fever" and other curses.

"How can you put so much devilry
Into that translucent phantom shred
Of a frail corpus?

Queer, with your thin wings and your streaming legs
How you sail like a heron, or a dull clot of air,
A nothingness."

Six species—Four stories

Figure 3

Linnæus in English

Portion of an old latin textbook

Biodiversity Heritage Library, courtesy North Carolina State University Libraries

The first English edition of Linnæus's Systema naturæ, translated by the British naturalist William Turton (1762-1836), was published (6 volumes in 8) in London between 1802 and 1806 under the title A General System of Nature.6 Charles Willson Peale knew of the translation, but there is no evidence that Lewis had heard of it, and if he had, it would have been of negative value to him, since the only species from America was Culex ciliatus (Fabricius), from the Carolinas.7

The "former insects" referenced in Turton's note on the genus Culex were 51 species of the genus Tabanus, in the family Diptera that were known at that time. Those silent, greedy "horse flies," feared for their extremely painful bites, are now known to number in the hundreds of species, and are subsumed along with deer flies (genus Chrysops) in the family Tabanidae.

Figure 4

Jan Swammerdam's Closeup

To see labels, point to the image.

Scientific illustration of a mosquito as described below

Special Collections and University Archives, W. E. B. Du Bois Library, University of Massachusetts Amherst

This engraving of Jan Swammerdam's drawing of his view of a mosquito as seen through his rudimentary microscope was the first close-up of the insect to be published–in Swammerdam's posthumous Bybel der Nature (1737-38; English translation as The Book of Nature, (1758). The naming of its parts advanced as successive entomologists studied the features, their relative locations and their functions. The mosquito's head is its control center, holding its sensory and feeding organs. Its thorax–a Greek word for chest–supports the six legs and two wings. In the female mosquito the principal function of the abdomen is to hold the blood meal, normally amounting to about 2.8 mg, or .3 mg more than the mosquito's body weight when empty. Each of the parts identified above, itself consists of an array of components. The halteres (pron. HALL-ter-eez), which Swammerdam did not discuss, are vestigal wings that function together as a gyroscopic balancing and guidance system that provides stability in flight. He didn't point out or discuss any of the mosquito's respiratory organs, which are simply holes, called spiracles, along the sides of the abdomen.

The process of understanding how each part of each member works developed over a span of three centuries, and it continues into the twenty-first century as more sophisticated microscopic technologies are employed. For example, the two maxillary palps ("feelers") together are now understood as parts of a mosquito's olfactory organs, through which they sense a potential host's emission of tell-tale carbon dioxide. Much of what is learned by scientists can help solve problems related to the control of mosquito populations. And so the discoveries continue, species by species, bit by bit.

Figure 5

Mosquito proboscis

Microscopic photo of the end of a mosquito probiscus

Courtesy of the BIODIDAC Project, University of Ottawa, Canada

Microscope slide of the tip of the labellar lobes, or lips, of a Culex's mouthparts, at the business end of a mosquito's proboscis (Greek pro, "in front;" boscis, "to feed"). Could Meriwether Lewis have imagined such a sensuous detail?

Six species. That's all Carl Linnæus listed under the genus Culex in the tenth edition of his Systema Naturæ, of 1759. As with most of the rest of his work, the descriptions were brief, in this instance amounting to seven words at most; the shortest stopping at only two words.1 Paltry help to even the most determined, objective explorer. But why would Lewis carry a copy of it. It was entirely written in the serious European scientist's language, Latin.

Lewis had the benefit of Owen's Dictionary2 in the expedition's library, but its treatment of the gnat–the British synonym for mosquito–was only a little more informative than Linnæus's. It described the genus in a mere 49 words:

In zoology, an insect of the fly-kind, called by authors culex. There are several species of gnats, distinguished partly by their size, and partly by the different colours with which they are variegated as black, brown, grey, yellow, &c. They belong to the order of two-winged flies.

Just "several species" of gnats or mosquitoes in the order Diptera. At the opening of the 21st century there were 3,500 known species of mosquitoes, and no one knew how many more remained to be counted.

Owen's definition of Culex, the Greek word for gnat, was no more helpful: "A genus of two-winged flies, the mouth of which is tubular, like a siphon, but exceeding slender, and filiform [thread-like]. Under this genus are comprehended the gnats, and humble-bees."3 Even if Lewis had tried to write up a specimen of Culex, he would scarcely have known where to begin. It would have seemed futile to apply the basic anatomical measurements such as he made of birds or bears—dimensions and weights, or qualities comparable to the colors and textures of feathers or fur. The results would have been so minute as to seem inconsequential compared with those of the megafauna–grizzlies, elk, moose and deer–or even the smallest avians, not to mention the gloriously colorful geometrics of butterflies. No wonder Aristotle had declared insects to be too small and insignificant to be classified among the animals at all. And no wonder most authorities after him had echoed that fallacy for the next 1500 years.

In 1803, the leading European expert on insects was a student of Linnæus's, the Danish entomologist and economist Johann Christian Fabricius (1745-1808), who published seven books on the subject between 1775 and 1804. All were in Latin, and thus would have been useless to Lewis or Clark. Although Fabricius never visited North America, he described and named a large number of insect specimens that were sent to him by American collectors—chiefly species known to cause negative economic impacts on agriculture, such as the flour beetle, the bean weevil, and the corn earworm—but no mosquitoes, which only annoyed people.4

A few naturalists and systematists had begun studying mosquitoes even before Linnæus entered the scene, but their results were as insubstantial as their specimen collections. In general, early entomologists were mainly fascinated by only four aspects of a mosquito's identity: 1) Its common names in various languages; 2) its second life-stage, the worm-like transitional phase; 3) its long feeding tube, or proboscis; and 4) its simple but searing coloratura hum, whispered impudently into the ear.5

1. A swarm of names

Even as the Expedition was being conceived and planned, and while it was underway, the onomastic brew continued to simmer. English entomologists and naturalists commonly called it a gnat, as they still do.8 German-born Private John Potts, of the Corps of Discovery, might have called it a grosser Mücke (large gnat) or a Stechmücke (biting gnat). François Labiche, George Drouilard and the other French-speakers in the party might have called it a cousin (derived from the Latin culex, midge) or a moucheron (very small fly– a term also applied to an annoying child—a brat).9 But ever since early Colonial days it has chiefly been known in America by its Spanish name, mosquito.

During the fifteenth century, Spanish explorers of South and Central America used the noun musca, or mosca—"fly"—to denote any two-winged insect. With the diminutive Spanish suffix ito added to the generic noun, "little fly" was a neutral name for the insect that some Spaniards called, more descriptively, zancudos—"long legs."10 Thus by the end of the sixteenth century the English explorer Richard Hakluyt  (c. 1552-1616) reported in the journal of his North American explorations, "Wee were . . . oftentimes greatly annoyed with a kinde of flie; . . . the Spanyards called them Musketas."11 In the United States, the Spanish nickname stuck, from then on.

Given the broad array of urban and rural American dialects that could be heard among the men of the Corps, and the fact that Noah Webster's efforts to standardize American speech habits still had a long way to go as of 1803-06, William Clark's perfect storm of orthographies may be viewed as proof that he cocked his ear to every voice, and was generally accustomed to transcribing what he heard phonetically, as closely as possible. As a result, in most instances we can hear exactly what he heard, although sometimes the exigencies of his official responsibilities derailed his best intentions, as when he wrote "Dekinsary" for dictionary.12 As to the word we spell mosquito, he essayed at least nineteen different guesses, among which his favorites were "musquetors" (used 41 times) followed at some distance by the enigmatic "musquistors" (11 times), "musqutors" (7 times), and "misqutors" (6 times). Perhaps they reflected nineteen subtly differing pronunciations that he heard–or thought he heard.13 Notice that every one of his spellings ends with the postvocalic r.14 Neither Clark nor any of the other journalists ever used the current spelling, "mosquito," which in fact may have first appeared in print in 1804.15

In its account of the word's etymology, the Oxford English Dictionary Online (2008) listed forty English-language orthographies that since the middle of the nineteenth century have been reduced to "mosquito." It does not, however, include the form "musquetoe" that Noah Webster used in the first edition of his American Spelling Book (1783). Nor does the OED's list include any of Clark's nineteen variants, which consistently reflect the South Midland dialect of Americanese English that he acquired as a teenager after his family moved to the vicinity of Louisville, Kentucky in 1784. Lewis added a twentieth solution to the array—"musquetoe." Consistent with a Virginia gentleman's manner, he usually omitted the postvocalic r that his co-captain habitually used.16 In the Compendious Dictionary of the English Language (1806), Webster introduced a simpler phonetic "musketoe"–"a vexatious insect." In his later American Dictionary of the English Language (1828) he expanded the definition somewhat, concluding with a reference to the itch and the swelling: "A small insect of the genus culex, that is bred in water; a species of gnat that abounds in marshes and low lands and whose sting is peculiarly painful and vexatious."

Lewis favored "musquetoe," as did Sgt. Ordway. Pvt. Whitehouse and Sgt. Gass used various spellings possibly copied from Clark and Ordway, plus others that may have been their own phonetic compromises. Cumulatively, the long effort to identify the "correct" spelling, which American authorities now agree is mosquito, comes to a total of sixty different solutions, not counting the additional versions in all other languages.

Almost without exception, every traveler during the eighteenth and nineteenth centuries complained about the mosquitoes, although few with as much vehemence and–up to a point–variety as the journalists of the Lewis and Clark expedition.

The -ology of it

The branch of zoological science dealing with insects acquired the name entomology during the second half of the eighteenth century, when naturalists' fields of inquiry had grown in variety and scope to the point where taxonomical tools had to be expanded proportionately. The word is a combination of entomo–from the Greek prefix ento, alluding to the segmented bodies (head, thorax, abdomen) of insects–and the suffix ology, meaning study. It first appeared in print in 1766, in a work by a British naturalist who acknowledged its descriptiveness, but personally objected to its use because "its barbarous sound terryfy'd" him; he preferred to call the science insectology.17

Drawings were helpful, too. In 1771 the English naturalist Gilbert White (1720-1793) wrote to the Welsh zoologist and ornithologist Thomas Pennant (1726-1798):

As far as I am a judge, nothing would recommend entomology more than some neat plates that should well express the generic distinctions of insects according to Linnæus; for I am well assured that many people would study insects, could they set out with a more adquate notion of those distinctions than can be conveyed at first by words alone.18

By 1823 the word had earned its place, and Thomas Say (1787-1834), the first academically trained entomologist in America, published his three-volume American Entomology, featuring 57 hand-tinted "neat plates" of beetles and butterflies "drawn from nature." It included only a few mosquitoes, which were still classified under the genus Culex.19 Among them were two species, which were to be identified some 70 years later as vectors of malarial protozoan parasites. One was C. quadrimaculatis ("four spots"), the other C. punctipennis ("pointed wings").20 In 1787 another naturalist contributed A"des aegypti from specimens collected on the Barbary Coast of North Africa. However, its responsibility for spreading yellow fever was not discovered until about 1900 by the Cuban physician Carlos Finlay and the American physician Walter Reed. In 1818 the German entomologist Johann Wilhelm Meigen (1764-1845) introduced the name Anopheles–a Greek word meaning "useless"–for the genus that included the species which a British physician discovered in 1898 to be a carrier of malaria.

Several minor studies of the genus were ongoing in Philadelphia about the time Lewis was there on his shopping and study visit, but popular interest in the mosquito generally stopped at the swelling and the itch. Few naturalists took the trouble to examine the little fly in detail, strictly on its own terms.


For two thousand years the knowledge and appreciation of insects was high-centered on the observations and theories of the Greek philosopher Aristotle (422-384 BC). The insect he called empis is believed to have been what we now call a gnat or mosquito. Today his term identifies a genus consisting of about 460 species, the most common of which is Empis livida, commonly called the dance fly after its erratic flight patterns21 Aristotle was convinced that insects in general were insignificant compared with the higher orders such as fish, birds, and quadrupedal mammals, because insects were so small that they were hard to study. For example, lacking the means to observe the reproductive process of the fragile mosquito, he concluded that their eggs were produced spontaneously.

However, with the invention of the single-lens microscope toward the end of the sixteenth century, the work of the Dutch naturalist Jan Swammerdam (1637-1680; Figure 4) was made possible, immediately moving the understanding of Culex forward. Swammerdam rejected the Aristotelian theory of spontaneous generation and progressive metamorphosis, and proved through systematic dissection and microscopic observation the organic continuity of development from egg to imago.22

For centuries naturalists considered the bite of the mosquito to be a mysterious but ostensibly deliberate gesture of vengance or retribution. In 1665 the English scientist Robert Hooke (1635-1703), a contemporary of Jan Swammerdam, published his Micrographia, containing copperplate engravings of insects, plants, and familiar objects such as the blade of a razor and the point of a needle, as seen through a microscope.

David Thompson (1770-1857), the Canadian explorer and cartographer who was a contemporary of Lewis and Clark, made some remarkably detailed and accurate observations concerning certain aspects of the mosquito's physiology:

The Musketoe Bill, when viewed through a good microscope, is of a curious formation, composed of two distinct pieces; the uper is three-sided, of a black color, and sharp-pointed, under which is a round white tube, like clear glass, the mouth inverted inwards; with the upper part the skin is perforated, it is then drawn back, and the clear tube applied to the wound, and the blood sucked through it into the body, till it is full; thus their bite are two distinct operations, but so quickly done as to feel as only one.23

Unfortunately, Thompson's journals, which were private documents belonging to the Hudson's Bay Company, remained unpublished until the early 20th century. But there was more to be learned. Early 20th-century entomologists learned that the mosquitoe's proboscis consists of six shafts. Four are for piercing the epidermis and searching for a blood vessel to drink from; that initial poke is usually so slight that all it elicits is a little slap at the tickle. The fifth shaft injects a bit of saliva that prevents the victim's blood from coagulating before the feeder's tummy is full. The sixth draws the blood. The body reacts to the incursion by rushing histamine to it, which causes the wounded blood vessel to swell, producing the bump. The swelling irritates the nerves in that vicinity, which is interpreted by the victim's brain as something to be relieved by rubbing or scratching.


1. Carl Linnaeus, Systema Naturæ, tenth edition, 2 vols. (1758; facsimile, New York: Stechert-Hafner Service Agency, Inc., 1964), 1:ppp. The first edition, published in 1735, consisted of only 11 pages; the tenth edition contained classifications of 4,400 species of animals and 7,700 species of plants, including many of each from North America.

2. A New and Complete dictionary of Arts and Sciences; comprehending all the branches of useful knowledge, with accurate descriptions as well of the various machines, instruments, tools, figures, and schemes necessary for illustrating them, . . . The whole extracted from the best authors in all languages, by a Society of Gentlemen. 2nd edition (London: Printed for W. Owen, at Homer's Head, in Fleet-street, 1764) 8 volumes in 4.

3. The humble-bee, more familiarly known in America as bumble-bee, represents a large genus (Bombus; Latin for "buzzing"; 250 species) of bees, some large, with a commensurately loud wing-generated buzz. Agriculturally, they are important as pollinators, but they do not store honey. They can sting, and sting repeatedly, but not unless disturbed. Meriwether Lewis observed, while camped near the Nez Perce on the Clearwater River in Idaho (May 30, 1806) that "the honey bee is not found here.     the bumble bee is." The honey bee, imported from Europe by the earliest settlers on the Eastern Seaboard, had migrated almost as far west as the Mississippi River, but did not reach the Pacific Coast until the 1850s.

4. E. O. Essig, A History of Entomology (New York: Macmillan, 1931), 622-25.

5. Sir S. Rickard Christophers, A"des aegypti (L.), the Yellow Fever Mosquito (Cambridge: University Press, 1960), 3.

6. It is accessible online in the collection of the Biodiversity Heritage Library, courtesy of the North Carolina State University Libraries.

7. The specific epithet ciliatus is Latin for "fringe."

8. Culex Pipiens is the scientific name, worldwide, for the common house mosquito. In the U.S. today, the word gnat officially denotes the dipteran Ceratopogonidae (ser-RAT-o-po-GAWN-ih-dye), a large family consisting of hundreds of species of very small (1-3 mm long) hematophagic (blood-sucking) flies variously called no-see-ums, sand flies, midges, or punkies. Some species are small enough to easily fly through ordinary mosquito netting. Some members of this family (which is now a subfamily) were first described by Johann Meigen (1764-1845) in 1803.

9. Larousse defined moucheron as Nom usuel des petits insectes diptères voisins de la mouche. Insecte diptère aux antennes courtes, au vol bourdonnant et zigzaguant—"Common name of a small two-winged insect related to the fly; a two-winged insect with short antennae, that flies in a zigzag manner like a bumblebee."

10. Christophers, 1-2.

11. Richard Hakluyt, The principall navigations, voiages and discoveries of the English nation: made by sea or over land (London: G. Bishop & R.Newberie, 1589), 568. Cited in Oxford English Dictionary Online s.v. "mosquito."

12. "Memorandum of articles fowarded to Louisville by Capt. Clark" from St. Louis. Moulton, Journals, 8:419.

13. Robert R. Hunt, "The Blood Meal: Mosquitoes and Agues on the Lewis & Clark Expedition." We Proceeded On, Vol. 18, No. 2 (May 1992), 4-10.

14. The addition of the sound of r following a vowel in regional or local pronunciations, as in the New Englander's lawr for law—or as shown orthographically in each of Clark's spellings of musquito.

15. In a travelogue by an Irishman that was published in London in 1800: "In the summer season you meet with rattle-snakes at every step, and mosquitoes swarm so thickly in the air, that to use a common phrase of the country, 'you might cut them with a knife.' The cold nights in the beginning of September effectually banish these noxious animals," in "Description of the River and Falls of Niagara," from Weld's Travels through the States of North America . . . During the Years 1795, 1796, 1797, in The Literary Magazine, and American Register, Vol. 2, No. 12 (September 1804), p. 432. American Periodicals Series Online (retrieved June 16, 2011).

16. A "postvocalic r is the sound of r following a vowel in certain regional or local pronunciations, as in the New Englander's lawr for law, and as shown orthographically in each of Clark's spellings of musquito.

17. In England during the 17th-19th centuries, "terrified" was often used for "annoyed." OED.

18. Gilbert White, The Natural History and Antiquities of Selborne (London: T. Bensley, 1789).

19. Thomas Say, American Entomology, or Descriptions of the Insects of North America. 3 vols. (Boston, 1859), 2:39–45.

20. A photograph of a wing of a specimen of Anopheles punctipennis may be viewed at (retrieved 4 June 2009).

21. Aristotle, The History of Animals, trans. D'Arcy Wentworth Thompson. Book I, Part 5. (retrieved 2008, May 27).

22. Imago (pron. ih-may-go or ih-mah-go) denotes the adult stage of an insect. (retrieved June 3, 2010).

23. J. B. Tyrell, ed., David Thompson's narrative of his explorations in western America, 1784-1812 (Toronto: Champlain Society, 1916), 24-25.