Late one April afternoon two surf casters wet their lines in the
Gulf of Mexico, off Cape Sable, Fla. They fished for sharks and
between them caught five blacktips, all more than six feet long.
As twilight descended, salt-marsh mosquitoes arrived in force.
Every few minutes their numbers seemed to increase
exponentially, like one of the 10 plagues visited on the house
of Egypt. The fishermen retreated to their tent and, except to
pee, stayed inside drinking beer and listening to sharks cut the
surface. At 2 a.m., in his haste to get outside before his
bladder burst, one man broke the zipper on the tent, which
allowed inside a Biblical cloud of mosquitoes. Then, in a
Florida rendition of the cliff scene in Butch Cassidy and the
Sundance Kid, the two men ran into the Gulf of Mexico and kept
company with the accommodating sharks till sunrise. At that
point only their lips were showing.
The two fishermen who told me their story at least had each
other for commiseration. Everglades National Park rangers tell
of a lone fisherman whose skiff broke down in nearby Whitewater
Bay. He spent the night submerged, breathing through a straw.
The late Dr. George Craig, a Notre Dame biology professor who
was considered the preeminent authority on mosquitoes, once
estimated that it would require 1,120,000 bites from the pesky
critters to drain all the blood from an adult human. Craig never
said where to test his supposition nor which of the world's
approximately 3,500 species of mosquitoes would be up to the
task of exsanguinating a human. One of his former graduate
students, George O'Meara, however, had an idea.
O'Meara, a professor of entomology at the University of
Florida's Medical Entomology Laboratory in Vero Beach, is one of
a team of scientists at the laboratory whose careers hover
around mosquitoes. He opts for the town of Flamingo, on Cape
Sable in Everglades National Park. At the height of the rainy
season--July through September--shallow pools in the mangrove
forest alternately flood and dry. If the cycles happen to be
spaced five or six days apart, two species of salt-marsh
mosquitoes, Aedes taeniorhynchus and A. sollicitans, proliferate
in astronomical numbers. Their eggs, laid on damp ground, mature
in five days,
June 23, 1996
O'Meara has conducted research in Flamingo for 25 years, and
every year he must apply to the national park for a permit to
collect mosquitoes. Laughing, he says, "You don't need a permit
to slap them." If the parking lot is empty of visitors when he
arrives and the ranger's white car is black with insects,
O'Meara is thrilled, for he knows that the mosquito population
must be intense.
Here is a story to place Flamingo's insect life in the proper
perspective. One summer in the early days of Everglades National
Park (established in 1947), a pesticide fogging truck had to
spray five times a day to make Flamingo tolerable for the few
summer staff members who lived there. Driven to distraction by
the biting insects, rangers called park headquarters near
Homestead, a comfortable 38 miles away, and asked permission to
pull back. Apparently, that summer mosquitoes near
Homestead--there are at least 40 species in the park--were
tolerable, and headquarters denied the request, suggesting that
the rangers were sissies. To make the point, one Flamingo ranger
followed the fogging truck and filled a large grocery bag with
mosquito carcasses. He sent the bag back to headquarters. The
next day a message reached Flamingo: Pull back.
Fixed to the bulletin board in the Flamingo Ranger Station is
the flamingo mosquito meter, which reports to park visitors what
the day's amplitude of biting insects is. The meter features a
picture of a large, nasty-looking mosquito whose proboscis
points to one of five categories: enjoyable, bearable,
unpleasant, horrible, hysterical. Next door, a gift shop sells a
popular bumper sticker that looks like a cross between ads for
an exterminator and for the Red Cross. It reads, I GAVE AT
Salt-marsh mosquitoes are not selective feeders; they're
opportunists. Several years ago I watched a cloud of them
engorge in the nostrils and around the eyes of an
eight-foot-long crocodile, which basked in the sun, seemingly
oblivious to the intrusion. When loggerhead sea turtles crawl
out of the Gulf of Mexico to nest in the bone-colored sand of
Cape Sable, every turtle sports an entourage of mosquitoes.
Outside O'Meara's office is a flight cage in which he and other
biologists have tested the response of various species to hungry
salt-marsh mosquitoes. Birds that rely on stealth or camouflage
to capture food--barred owls, green-backed herons, black-crowned
night herons and great blue herons, for instance--wait like
stones, rarely flinching, while clouds of mosquitoes ply their
trade. Active feeders such as white ibis and snowy egrets twitch
and bite, often eating the bugs that try to bite them.
The walk-in flight cage is built like a large wood-framed screen
porch. Some years ago, O'Meara enlarged his study population to
include two officials of the Accutronics Corporation, which at
the time marketed an antimosquito device called the Mosquito
Hawk. The company claimed that the Mosquito Hawk mimicked the
noise made by the beating wings of a dragonfly, a major mosquito
predator, and thus kept mosquitoes at bay. The inventor agreed
to a test in the cage. To prepare for it, O'Meara starved
several thousand female salt-marsh mosquitoes (only females suck
blood; males sip plant juices). The inventor of the Mosquito
Hawk entered the flight cage, four buzzing black boxes fixed to
his belt. The mosquitoes began to feed, undeterred by the
high-pitched sound. Within seconds the man turned to flee, but
the door had jammed. Panic reigned until O'Meara rescued him.
O'Meara has been bitten by salt-marsh mosquitoes so many times
in the course of his research that he has become immune to their
bites--no slapping, no itching, no swelling. Inhaling
mosquitoes, however, can still cause discomfort. A hungry female
mosquito, which needs a high-protein meal of blood to produce a
clutch of eggs, is attracted to carbon dioxide and lactic acid,
both of which are given off by respiring and active birds and
mammals. She also may key in on an animal's profile and on
dark-colored clothing, like the olive-green uniforms worn by
rangers in Everglades National Park. Drinking ginseng tea or
eating bananas, vitamin B, garlic, brewer's yeast or Mrs. Paul's
Fish Sticks--all suggested as can't-miss home repellents--fails
to keep mosquitoes away. Commercial bug repellents may keep
mosquitoes from biting, but they contain DEET, the active
ingredient in most repellents, which is absorbed by the skin and
has been linked to seizures and deaths. It also dissolves
plastic and vinyl, which renders binoculars and cameras
permanently sticky. Although acquired immunity may be reliable
and safe--the Zen approach to living with mosquitoes--who would
want to get bitten the requisite several thousand times each
year for many years to become desensitized?
Behind O'Meara's office is a web of canals sliced into a
frost-stunted mangrove forest that feeds Indian River, a mile or
so away. On this day it was sunny and warm, in the low 70's, and
would have been good weather for salt-marsh mosquitoes except
that it hadn't rained in more than a month and the temporary
pools had all dried out, leaving tableaux of opossum and raccoon
tracks in the caked mud. Above the tide line, shaded by black
mangroves, were the long, curved burrows of the great Atlantic
land crab. The burrows, which extend to the waterline, are also
the home of the crabhole mosquito, one of O'Meara's favorites.
He poured water down a burrow, and a congregation of mosquitoes
rose from the hole. The males' long antennae, which droop
forward like an extra set of legs, are used to shepherd females
still in their pupal stage. When an adult female sheds her pupal
case, she is quickly bred by her tending male. Both sexes rest
on the walls of the burrows by day and feed by night, the males
on nectar or fruit juice and the females on either blood or
sugar from fruits and flowers. The newly emerged crabhole female
produces her first clutch of eggs on a blood-free diet. If she
has stored enough food in her body from her days as a larva, she
may stay with sugar for the second clutch and never suck blood.
"They're nice mosquitoes," O'Meara chortled.
O'Meara is 54 years old, a white-haired and blue-eyed migrant
from the Northeast. Next to Jack Kerouac and textiles, he is one
of the better-known products of Lowell, Mass., a round, jolly
man who broadcasts exuberance for the world's most deadly group
of insects. As a boy he never had a bug collection and never
dreamed of biology, let alone a lifetime of mosquitoes. O'Meara
once hoped to be a ballplayer, to patrol the outfield at Fenway
Park, but he couldn't hit a curveball. At Notre Dame, George
Craig introduced him to the rewards of mosquito research. He
stayed on to complete his doctorate before moving, 27 years ago,
to Florida and its 70 or so mosquito species.
Except for a white Aedes sollicitans that his wife, Mary,
crocheted on one of his ties, nothing in the O'Meara household
suggests mosquitoes. None of his four grown children followed in
their father's footsteps. "There's still hope for my
10-year-old daughter, Meg," he says. "But I wouldn't count on it."
Returning from the salt marsh, O'Meara walked along a trail
through a live oak hammock. The trees were tall and draped with
Spanish moss, and for the most part they blocked out the sun.
Here and there pines and cabbage palms punctuated the forest.
Some of the rough-barked oaks supported tank bromeliads, air
plants that look like the tops of pineapples and hold water
between the tight weave of their long, tapered leaves. O'Meara
pulled his wife's turkey baster from his back pocket, inserted
it into a bromeliad and squeezed the ball, removing half a dozen
mosquito larvae, which he squirted into a petri dish.
One larva was nearly half an inch long and had an oversized head
that was four times the size of the others'. The big one was a
predator of other species of mosquito larva. Its prolonged
development puts it in contact with several hatches of prey,
which it devours before maturing. Later, in a warm, humid cage
in the center's laboratory, O'Meara pulled out the adult
incarnation of the same species. These are huge and beautiful,
more like tiny butterflies than large mosquitoes--blue-black
bodies with phosphorescent stripes, iridescent purplish wings.
The lower legs are white, as though the mosquitoes are wearing
stockings, and the males' antennae are bushy. As adults the
females imbibe only plant juices. O'Meara squirted the big one
into a bromeliad and wished it well. "Go, do your job," he said.
As I left Vero Beach after seeing O'Meara, I remembered a
previous trip, in 1993, during which it rained, a long, hard
rain. When the storm finally blew out to sea, the sun reappeared
and the million raindrops, on a million leaves, made South
Florida sparkle. The air smelled fertile. Four days later, in
Everglades National Park, much of the Christian Point Trail,
which winds through an old buttonwood forest, lay beneath six
inches of stagnating rainwater seething with life. I dipped a
mayonnaise jar into the opaque broth, held it to the light and
watched thousands of salt-marsh mosquito larvae snap up and down
like grains of rice in a rolling boil.
Six days after the rain, adult salt-marsh mosquitoes began
emerging from the flooded ground. Every hour their numbers
seemed to swell. I had a flat tire that morning and,
unfortunately, changed it dressed in sandals, shorts and a
paper-thin shirt. By midafternoon my ankles and arms looked like
a relief map of the Appalachian Mountains and I was scratching
my back against a tree like a bear.
The most chilling Flamingo mosquito story I ever heard concerned
a fisherman on Cape Sable who became separated from his
companions late at night and couldn't find the beach again.
Fearing the worst for their friend, the fishermen organized a
ranger search party. Several hours later the missing man was
found behind the beach, in Lake Ingraham, floating on an oil
drum. His arms and face were caked in mud, his eyelids swollen
shut from bites he couldn't escape. When the rangers arrived, he
mumbled, "They're buzzing. They're buzzing."
Naturalist Ted Levin, who lives in Thetford, Vt., is at work on
a book about the Everglades.