Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, July 10, 1994 TAG: 9407290004
SECTION: EXTRA PAGE: 11 EDITION: METRO
SOURCE: KAREN UHLENHUTH KANSAS CITY STAR
DATELINE: MANHATTAN, KAN. LENGTH: Medium
There's probably nothing that has proved such a boon to this particular species as deep, plush, curl-your-toes-in-it pile carpeting.
``The principal reason we're having so much trouble with fleas today in the home environment is the advent of wall-to-wall carpeting,'' said Mike Dryden, veterinarian, parasitologist and flea-man extraordinaire. ``It's a pretty good matrix for flea development. It absorbs moisture out of the air and serves as a protective micro-climate against humidity and temperature fluctuations and insecticide application.''
Dryden, an assistant professor of parasitology here at Kansas State University, has made it his business to know what makes cat fleas tick - and what makes them go belly-up. He began to really take notice of the little buggers when he started in veterinary practice about 10 years ago.
``One of the things that frustrated me was that I couldn't get control over fleas, no matter what I did.''
In 1986, after about two years in practice, Dryden went to Purdue University in West Lafayette, Ind., to get a doctorate in parasitology. He cast around for a research topic.
``I found out that we knew virtually nothing about the biology of fleas on dogs and cats, and I realized the world was open before me,'' he said.
He stepped into the void and claims he's the only veterinarian in the United States researching flea biology and control. Dryden has acquired an impressive stash of flea facts. Such as:
A newly emerged flea can live two weeks on your carpet, thriving quite nicely, thank you, on skin dander, flea feces and fungus. A flea riding around on a dog or cat can hang on for more than 100 days. But one that's dislodged from a host animal will likely die within four days.
Fleas dislike feeding on humans and will do so only under great duress. Researchers aren't sure why, but Dryden speculates there's something in our sweat glands that offends them.
Fleas travel by jumping - about 6 to 10 inches at a time. Dryden says he's ``still amazed at the number of people who think fleas fly.''
The most common disease afflicting dogs in the United States is flea dermatitis.
Americans spend about $1 billion annually to combat fleas.
In a laboratory at the K-State veterinary school, Dryden's research team goes through between 5,000 and 15,000 fleas weekly. They cultivate a steady supply with the help of a few cats they get from the local Humane Society. They put a dozen or so fleas on each of the cats and keep them in special cages with flea-egg collection devices.
Despite his convenient and steady flea supply, Dryden has traveled to Tampa in search of fleas for field work. It was more of a political than pragmatic act, however.
``In flea circles,'' he said, ``they don't think you've dealt with fleas until you've dealt with Florida fleas.''
They aren't different, just more numerous. Dryden and his colleagues picked 5,000 fleas off of one dog they encountered there.
While fleas don't thrive on standing water, as mosquitoes do, Dryden said that rain boosts their populations because it increases the relative humidity.
``The larval stage of the flea is very susceptible to drying. If the relative humidity is below 30 percent to 50 percent, they die.''
Although some flea eggs are laid and hatch in shady places outside, the real flea action is between the fibers of your carpet. The lucky fleas that find a dog or cat to latch onto are carried inside, where their eggs roll off of your pet and onto the floor. Females living on a host produce between 20 and 40 eggs a day.
Over the course of a few weeks, the egg hatches a larvae (worm), which crawls around for about a week, then spins a silk cocoon. A couple weeks later it's out and looking for blood.
Dryden and his team have learned from their studies that fleas move toward light, air currents and especially shadows - which could indicate a blood meal in the neighborhood.
Based on their observations, Dryden and two colleagues - entomologist Alberto Broce and research associate Kent Hampton - developed a flea trap. It has been patented by K-State and licensed to a manufacturer that plans to sell it worldwide.
The trap sends out an intermittent yellow-green light, and it is timed to turn off for five seconds out of every 10 minutes. The color simulates light filtering through grass, Dryden explained.
``When we blink it, they think it's a shadow and jump through the trap.''
by CNB