The Great Mosquito Safari: A Collecting Trip with William Horsfall

Dr. William R. Horsfall, professor emeritus of the Department of Entomology, University of Illinois, passed away at the age of 90 at his home at the Clark-Lindsey Village, Urbana, IL, on November 18, 1998. He is survived by his wife of 68 years, Annie Laurie Ellis Horsfall, and was preceded in death by a sister and two brothers.

Dr. Horsfall was born on January 11, 1908, in Mountain Grove, MO, but spent most of his formative years in southwestern Arkansas where his father served as President of what is now the University of Arkansas at Monticello and his mother served as that institution’s first Dean of Women. After receiving his B.S. degree in biology from the University of Arkansas in 1928, and his M.S. degree in agriculture from Kansas State University in 1929, Dr. Horsfall entered into study under Professor G.W. Herrick at Cornell University and earned his doctorate degree in entomology in 1933. He taught at Cornell for a time and then, up until World War II, he held faculty positions at the University of Arkansas-Fayetteville and South Dakota State University-Brookings, where he was also Head of the Department of Biology.

During World War II, Dr. Horsfall served in the Pacific Theatre as Commander of the U.S. Army’s 17th Malarial Unit. After 3 years of service, he was discharged as a lieutenant colonel and rejoined the entomology faculty at the University of Arkansas-Fayetteville. Dr. Horsfall remained active in the U.S. Army Reserves after his discharge and retired from this activity in 1965. In 1947 he joined the Department of Entomology at the University of Illinois-Urbana-Champaign as an assistant professor in medical entomology, a position he held until his retirement as professor in 1976.

Most mosquito people will remember Dr. Horsfall as the scholarly master of the bionomics and management of mosquitoes, particularly floodwater varieties. He actually began to develop his basic philosophies about insects and their control while he was working on such insects as grapevine sawfly, Erythraspides pygmaeus (Say) as a student at Cornell University. His conception of insect bionomics was strengthened and fine-tuned while working on meloid parasitoids of grasshoppers at South Dakota State University. Dr. Horsfall’s favorite quote to his students stemming from that era of his career was, "Effective control measures are dictated by the bionomics of the insects." Unfortunately this critical concept was lost to us during the ‘chemical age’ of 1945-1965, but was considered a novel approach with the advent of the integrated pest management paradigm of the 1970’s.

Many having known Dr. Horsfall personally as well as professionally point to his military experience as the time when he began to see the potential for applying his basic philosophy to manage mosquitoes and mosquito-borne diseases. Armed with the bionomic information he had gathered on the mosquitoes of New Guinea, and with oil as his only larvicide, he led his malaria survey unit to accomplish the near elimination of malaria as a problem on that island.

Dr. Horsfall’s scholarly potential became fully kinetic when he joined the entomology faculty at Illinois. In this atmosphere, he developed and taught a variety of courses focusing on insect bionomics, insect control, and medical entomology. His research efforts were centered on mosquitoes, mosquito-borne diseases, and their control. In the process, Dr. Horsfall also mentored some 21 doctoral and 20 M.S. degree students in medical entomology. Over his career, Dr. Horsfall published five books and more than 140 scientific papers and bulletins. An active member in the American Mosquito Control Association, the Entomological Society of America and many other professional organizations, he served as a consultant to governmental and academic agencies worldwide, including the World Health Organization, National Science Foundation, Department of Defense, U.S. Public Health Service, U.S. Environmental Protection Agency, U.S. Department of Agriculture, and the Tennessee Valley Authority. Dr. Horsfall was a founder of organized mosquito control in Illinois and was an organizer, charter, and first honorary member of the Illinois Mosquito & Vector Control Association.

Dr. Horsfall received many honors for his scholarly achievements and contributions to entomology and science in general. He was the first recipient (along with Maurice Provost) of the AMCA’s Harold Gray Memorial Medal of Honor and received such other prestigious awards as AMCA’s Distinguished Service Award, the American Society of Tropical Medicine and Hygiene’s Harry Hoogstraal medal, the Finnish Zoological Society’s Award of Merit, and the University of Illinois’ Wakefield Award for Excellence in Teaching. Also, in expressing his loyalty to the affairs of the University of Illinois, the institution honored him with membership into the President’s Council, and the Centuria Circle, its highest donor recognition award. Dr. Horsfall and his wife, Annie Laurie, were also recognized by the University for their generous support to the University Library and the Spurlock Museum of World Culture.

Despite all the awards and recognition Dr. Horsfall received for his scholarly achievements, he found his greatest satisfaction and reward in his students. He took great pride in his entomological pedigree, which began with Professors Comstock and Herrick and extended on through him to the students he mentored. As a mentor, Dr. Horsfall was a demanding taskmaster and the stories lovingly abound among his former students as to who had it the toughest. However, his gruff nature was only a veneer; for, underneath the rough exterior, there was a true humanitarian who cherished his association with students. He understood that, for a student to become a competent professional entomologist, he or she had to be tempered with hard work and discipline in and out of the classroom. The Horsfall pedigree, known as the "Horsfall Mafia," now extends to the third and fourth generations.

Dr. Horsfall students will agree that, while he was cap-able of such detailed and erudite work as embryonic development of mosquitoes under thermal stress, at the same time, he kept a strong connection to the practical roots of entomology. Considering his clear communication skills, acute scientific instinct, total honesty, curiosity, and warm humility, Dr. Horsfall was the ideal model of an entomologist for his students. He will be sorely missed but his legend and legacy will continue to live on in his students and their memories of him as teacher, mentor, counselor, and friend. "Rework" no more! The "Doc" has laid down his red pen. [back to top]

The Great Mosquito Safari: A Collecting Trip with William Horsfall
by George W. Swenson, Jr., Professor Emeritus, Department of Electrical Engineering
Reprinted with permission from the author

The faithful Seven-One-Papa was fueled and ready on the ramp of Illini Airport. The special trailing-wire antenna for the high-frequency radio was rigged and ready to be reeled out when needed. The twin 160-horsepower engines had had their 100-hour inspections and were certified in A-1 condition. The sextant and almanacs were aboard and our wristwatches had been carefully calibrated. We were only two on this trip—no use carrying extra weight, so the two rear seats had been removed. In their place was strapped a strange collection of equipment, representing the fieldwork necessities of an entomologist and a radio engineer, respectively. Of course, the load included sleeping bags, fishnet, axe, cooking kit, tent, rations, and other emergency gear required by Canadian regulations for wilderness flights.

Bill’s wife came to see us off. Annie Horsfall had witnessed the departures of many expeditions, apparently. She murmured to me, "Don’t let Bill feed more than 5000 mosquitoes per day. It makes him sick." I looked at her in disbelief, but she seemed perfectly serious. Still, I thought she must be pulling my leg. Little did I then know!

Bill’s mission was two-fold. He had a notion that mosquitoes breeding in an environment of relatively high radioactivity might have evolved some mutant forms. We’d collect some specimens on the tailing dumps of the old radium mines on Great Bear Lake, far up in the Northwest Territories. He also wanted specimens from the barren arctic tundra to study what developmental adaptations the insects make in response to extremely severe environmental conditions.

My job was to overhaul the radio equipment, install new antennas, train the new operator, and generally show the flag at our satellite tracking station at Baker Lake, Northwest Territories. Baker Lake is an Eskimo village in the barren lands, hundreds of miles north of the tree line. It should be an excellent place for the kind of studies Bill had in mind. A year and a half earlier I’d visited there in winter, and could certify to the extreme cold and violent winds the over-wintering mosquito eggs would have to survive.

Our route took us directly from Urbana, Illinois, to Winnipeg, Manitoba, an uneventful flight in good weather, with a stop at Bemidji, Minnesota, for fuel. Seven-One-Papa, the Piper Apache, purred along contentedly while I explained to Bill the operation of the VHF Omnirange, the automatic direction finder, the directional gyroscope (DG), and other navigational aids. I even practiced calculating the azimuth of the sun and setting the DG without reference to the magnetic compass, a trick we’d have to use when flying within a few hundred miles of the magnetic pole.

At Winnipeg we cleared Canadian customs, refueled, and found a hotel for the night. Next day we proceeded north-west between Lakes Winnipeg and Manitoba 640 km (400 mi.) to Flin Flon, on the Saskatchewan border. Flin Flon is a mining town on the rocky Laurentian Shield among a myriad of lakes. There was an excellent airport, 5 miles from town by air but 20 miles by the road that meandered among the lakes. There was a taxi in town, but no telephone at the airport with which to summon it. There was a phone in a booth by the runway with which one could request a weather forecast. Unfortunately, these forecasts were only good for a 4-hour period, and were usually 6 hours late, by which time we already knew what the weather had been. This weather service was not available in town either, but only from that particular phone. Clearly communications were going to be a problem as long as we were in Flin Flon.

A fisherman with a pickup truck solved our immediate problem by taking us to the hotel in town, where we had a good supper in the Chinese restaurant, one of Western Canada’s ubiquitous institutions. A good night’s sleep was next on the agenda to prepare us for a long day’s northward flying, first to Yellowknife, then to Great Bear Lake.

The weather was not encouraging on June 22, but we took advantage of a little break in the clouds to fly toward Yellowknife, hoping the clouds might lift toward the north. But our bad luck stayed with us; 75 miles out we were turned back by thick clouds reaching right to the ground. We followed our ADF back to the Flin Flon broadcast transmitter, then landed for refueling and another night in town.

We awakened on June 23 to rainy, gray skies and im-possibly poor visibility. We taxied to the airport anyway, to suffer hours of frustration trying to get timely weather forecasts. Back to town for another night. Time, at least, for exploring this interesting town, built on a rock so solid the utilities normally buried below frost line are here on the surface, enclosed in boxlike wooden ducts insulated against the cold.

By great good fortune on June 24 we were able to get timely weather predictions for a flight to Churchill, Manitoba, 640 km (400 mi) to the northeast on Hudson Bay. If we left immediately we could make the trip under visual flight rules and be there before dark. We couldn’t spend all summer trying to get to Great Bear, could we?

The flight was across a true, trackless wilderness, away from all established air routes and radio aids. The sensation of solitude has always thrilled me, and here we had 3 hours with never a road, a village, a wisp of smoke in sight. Thirty, even 20 years ago one could easily find such places in Canada and Alaska. Now, sadly, they have become all too rare, as the network of roads, airports, and radio beacons spreads inexorably into the remotest parts of North America. This was my first visit as pilot-in-command, and I was fascinated by the hangar talk of the local bush pilots and airline personnel: unpublished but useful radio frequencies, a rumored cache of aviation fuel at such-and-such a lake, a new emergency landing strip at so-and-so mining camp, and other valuable gossip. The station manager of Transair, Ltd., the regional airline, took us home for dinner and befriended us in many ways. He later undertook to collect mosquitoes for Bill over a period of years.

Bill wanted mosquito specimens from several locations: live, biting, pregnant females that can be counted on to deliver eggs when they arrive back in the Illinois lab. Churchill was our first good chance, so I got a lesson in collection technique. The basic equipment consisted of a plastic tube, about a centimeter in diameter and ten centimeters long with a nylon screen cemented over one end. A small cage is provided, the size and shape of a snuff can, with top and bottom of cork and cylindrical side of window screen. Bill demonstrated the capture technique. Sit on a rock with sleeves and pants legs rolled up. Only pregnant female mosquitoes bite, so one is assured of catching the right ones. When an insect lands on bare skin, the open end of the tube is placed over her, whereupon she flies upward into the tube. The tube is rapidly moved to another one, and another. When a dozen or so are accumulated, the open end of the tube is inserted into a hole in the top of the cage and the collector blows gently into the screened end to move the mosquitoes inside. The cage is stoppered, and the whole process is repeated until the cage has about 200 specimens inside.

Bill is very adept at this, and indifferent to the obvious hazards. In fact, he seems to have substantial immunity to the insects’ toxins, acquired by years of exposure. I, on the other hand, have a well-ingrained distaste of mosquito bites. I evolved my own collecting technique, involving only one bare arm at a time. Naturally, my collecting rate was much less than the norm, but after all, I wasn’t getting paid for this.

Bill wanted the mosquitoes to deliver eggs as soon as they arrived at Illinois. To do that they must have a blood meal before the return flight. Bill’s method was to place a screened cage against his bare chest, whereupon he would instantly be bitten by 200 ravenous, single-minded insects. To achieve the maximum possible production, he hinted rather strongly that other volunteers would be welcome, but I decided that my obligation to science would extend only to service as pilot, navigator, general expediter, and cheerleader. We collected several crates of mosquitoes in cages, which were stored in a hangar at Churchill to be picked up on our return trip.

The flight to Baker Lake was also uneventful, but very interesting. Churchill is at the northern limit of trees; beyond is only tundra. Still, the land is beautiful in an austere fashion, dotted with blue lakes amid the gray-green grasses and sedges, with visibility that is spectacular in the clear, arctic air. A smooth landing, followed by a trip to the village in a dump truck, and we settle into our quarters in the government laboratory. Baker Lake, is connected with Hudson Bay by Chesterfield Inlet, a 200-mile-long freshwater channel. Supplies came in by barge in the summer, so it’s a natural place for a government weather station, magnetic observatory, and regional administrative headquarters. A corner of the magneticians’ laboratory is available for our satellite-monitoring equipment, gathering data for studies of the ionosphere.

One thing puzzled us when we opened the door of the plane after landing at Baker. Where were the hordes of mosquitoes we’d learned to expect? We’d telegraphed ahead before leaving Illinois and had been told the snow was mostly gone and the tundra was dotted with meltwater pools. There should be mosquitoes, but there weren’t. This was a serious setback, especially after our disappointment at not reaching Great Bear Lake. A quick investigation of the pools showed them to be alive with mosquito larvae, prompting me to ask why we shouldn’t bring back larvae instead of adults. Because we haven’t the means, and because it’s not an efficient way to get eggs, Bill explained, as half the larvae are males. Still, it would be worth a try, as an alternative to complete failure.

The Hudson Bay Company store, surprisingly, had dozens of picnic-sized thermos bottles in stock. We bought them all, as well as a white-enameled dipper. We quickly gathered a large number of larvae and incarcerated them in the bottles, in meltwater exactly the same temperature as that in the pools. They’d have to be maintained at that temperature until they metamorphosed into adults in Urbana. We froze ice cubes of non-chlorinated meltwater in the kitchen freezer, and tended the larvae daily.

Of course, they had to be fed, too, but fed what? Bill didn’t know what these particular larvae ate, so he set out to learn. After a couple of hours belly-down beside several pools, he announced his finding: "Lemming droppings!" Lemmings, those legendary Arctic groundsquirrels, were everywhere on the tundra, so it shouldn’t be too much trouble laying in a suitable supply of rations for our larvae. All this activity required Bill to roam fairly widely about the tundra while I remained in the village tending to my electronic affairs. The tundra is rolling, if not actually hilly, but essentially devoid of landmarks. It would be easy for a novice to get lost, so it seemed a good idea for Bill to have a guide. The village fathers assigned the task to a teenaged Eskimo boy, who proved an invaluable assistant and an unerring pathfinder. The two of them spent hours on hands and knees before pools and lemming burrows, and I’d have paid a lot for a translation of the commentary in the Eskimo community regarding the habits and interests of visiting white men.

After 3 days Bill and I had completed our respective chores. The larvae were apparently thriving in their thermos bottles on their remarkable diet. It was time to head for home. The weather at Baker Lake looked fine and clear and the radio report from Churchill was good. We filed a flight plan for Churchill under visual flight rules and set out bright and early. We climbed to 9000 feet and headed south across the lake, then made a bee-line across the tundra. More bad luck! About 50 miles out we ran into impenetrable weather, a snowstorm, and had to turn back.

Another night at Baker Lake, and more waiting for weather reports from Churchill, relayed by Morse code via Coral Harbour, hundreds of miles to the north on Southampton Island. Next day we set off again, this time reaching Churchill easily, and there picking up our adult mosquitoes and pro-ceeding southward again.

Armstrong, Ontario, is our next stop, at the northern end of Lake Nipigon. It’s a long flight from Churchill, the long-est of the entire expedition, stretching our fuel capacity to an uncomfortable degree. Good weather allows us to enjoy one of the most beautiful, wild stretches of forest country in North America. Careful navigation is important here, too as we’re flying well off the regular air routes.

A small timber-industry town, Armstrong is on the trans-continental rail and air routes, but is hardly a sophisticated tourist center. We found a room in a tiny, primitive hotel over the town bar. The night began with an hours-long riot in the barroom downstairs, as lumberjacks and cat-skinners worked off the week’s tension, and ended in the wee small hours with a violent battle between the hotel manager and his wife in the room next door. Screaming and yelling, punctuated by the thudding of fists, kept us awake all night. Should we intervene, or try to locate the police? There is no telephone. We’re far from our own turf, uncertain whether this is a routine occurrence or a real emergency. Daybreak ended our indecision and we hastened to the airport for a short trip to Thunder Bay and outgoing customs inspection.

Next, we filed a radio message to U.S. Air Traffic Control, requesting incoming customs and immigration inspection, and took off across the middle of Lake Superior. The Big Lake is always beautiful and somehow mysterious. The route leads directly across Isle Royale National Park, from the air a lake-spangled green tapestry laid upon the blue sea, partially shrouded in mist. A few lake freighters move below us, carrying grain and iron ore from Duluth to Sault Ste. Marie. Then we cross the tip of the Keweenaw Peninsula and maneuver for a landing at Houghton County Airport.

The customs inspector’s face registers surprise when we announce our cargo, and he examines meticulously Bill’s U.S. Department of Agriculture permit for importation of live mosquitoes. A car pulls up to the ramp and my father and mother emerge, summoned by telephone from Thunder Bay. We motor to their home in nearby Houghton, to spend the night and to collect still more mosquitoes along the shores of Portage Lake, my boyhood playground.

Mother’s refrigerator provided ice cubes, of water first boiled to eliminate chlorine. We clustered around the kitchen table, tending our insect charges, feeding them and cooling their water to the proper temperature for the last leg of the trip back to Urbana. The episode made an indelible impression on Dad and Mother, providing stories for Rotary Club and Church Circle luncheons in subsequent years. They capitalized on it many times.

As have I. [back to top]

Entomology