A typical crane fly on the outside of a building. Photo credit: Carrie Stevenson, UF IFAS Extension
All my life, I’ve known them as mosquito hawks. Built like extra-large, spindly-legged versions of mosquitoes, they look a bit intimidating. However, growing up we were told they were harmless and actually fed solely on mosquitoes. In the days before Google, I just accepted it as fact and was glad to see them around.
In early March, there was a bit of an invasion of these insects. I started seeing them everywhere outdoors and inside my office building. They are slow movers, bouncing in the air more than flying. After several days of seeing them everywhere, though, they pretty much disappeared.
Several crane flies appear to have met their demise inside my office building. Photo credit: Carrie Stevenson, UF IFAS Extension
Like much folk wisdom accrued through my life, the story of the mosquito hawk is not totally true. They are harmless, that much is correct. While many people do know them as mosquito hawks, the accepted common name is the crane fly. Crane flies come in a wide variety of sizes and colors, ranging as some of the smallest and largest species in the fly Order, Diptera. Their diversity is rather mind-blowing, with the Family Tipulidae including about 15,000 species of crane flies worldwide.
Crane fly larvae live in aquatic environments and feed on decaying plant material. Photo credit: North Carolina State University
As for being voracious predators of mosquitoes, we have no such luck. Crane flies barely eat at all, because their adult life span is as short as those two weeks I recently noticed them around. They spend most of their lives as aquatic larvae, living in streams, pond edges, and rotting vegetation. Adults do not have the right mouth anatomy to eat other insect prey, instead drinking only by sponging up water in dew form or taking nectar from plants. Their primary purpose in adulthood is to complete the mating process. Females lay eggs near water, hence the location as larvae. After this hedonistic spring break experience of adult life, they die.
Crane flies, in both larval and adult forms, are popular snacks for other wildlife. The adults are easy targets for birds and bats. The larvae, which in some species are as large as a pinky finger, are tasty morsels for fish and amphibians. During their larval existence, crane flies ingest debris, helping with the decomposition process and filtering the water bodies they live in. Despite their short life span, crane flies make an outsized contribution to the food web.
Recently, I’ve been asked about a deer fly trapping method that I wrote about a number of years ago. So, here it is. This aggravating insect is active now.
Deer flies, which are in the horsefly family, are annoying as they repeatedly and persistently dive for their victims until they inflict a painful bite.
Dr. Russ Mizell, now retired UF/IFAS Extension entomologist, experimented with a method to trap this insect. Mizell wanted to identify the optimum shape, size, color and speed to attract deer flies. If successful, he could temporarily remove a deer fly population long enough to enjoy an outdoor gathering without being bothered by deer flies.
Mizell said he started the research as a high school science project with his son but “it got so interesting, I just kept doing it.”
Deer flies wait for prey to walk before attacking. So, they are highly attracted to movement.
With this in mind, Mizell and his son decided the best way to snare deer flies was to “troll” for them from a slow-moving vehicle. Working in spring and summer when deer flies are most prominent, they set out to discover what kind of trap worked best.
They built a test platform on the hood of their vehicle that could troll seven different shapes at once. They ambled along in deer fly-infested countryside for set periods of one to five minutes, testing pyramids, squares, balloons, plant containers and other shapes, all coated with Tanglefoot (commercially available sticky spray for insects), then counting immobilized prey. They tried black, tan, blue and shapes of other colors suspended from various heights.
The trap that enticed the most deer flies proved to be a 6-inch flowerpot painted bright blue and coated with Tanglefoot. This trap captured as many as 30 deer flies in a one-minute test. It worked best when suspended three to six feet above the ground and trolled no faster than 10 feet per second or about 7 miles per hour.
The traps are remarkably effective, Mizell said. “Many times, after running the traps through an area, we found there were no deer flies left,” he said. “You trap them out for a short period until they repopulate the area.”
The traps also work when attached to a baseball cap and trolled by the hat’s wearer. But instead of attaching a flowerpot to your cap, you could attach a blue drink cup painted with Tanglefoot.
Despite its effectiveness, its aesthetic appeal leaves something to be desired.
A natural disaster such as Hurricane Michael can cause excess standing water which leads nuisance mosquito populations to greatly increase. Floodwater mosquitoes lay their eggs in the moist soil. Amazingly, the eggs survive even when the soil dries out. When the eggs in soil once again have consistent moisture, they hatch! One female mosquito may lay up to 200 eggs per batch . Standing water should be reduced as mush as possible to prevent mosquitoes from developing.
You should protect yourself by using an insect repellant (following all label instructions) with any of these active ingredients or using one of the other strategies:
DEET
Picaridin
Oil of lemon eucalyptus
Para-menthane diol
IR3535
An alternative is to wear long-sleeved shirts and pants – although that’s tough in our hot weather
Wear clothing that is pre-treated with permethrin or apply a permethrin product to your clothes, but not your skin!
Avoid getting bitten while you sleep by choosing a place with air conditioning or screens on windows and doors or sleep under a mosquito bed net.
Now let’s talk about mosquito control in your own landscape.
Let’s first explore what kind of environment in your landscape and around your home is friendly to the proliferation of mosquitoes. Adult mosquitoes lay their eggs on or very near water that is still or stagnant. That is because the larvae live in the water but have to come to the surface regularly to breeze. The small delicate larvae need the water surface to be still in order to surface and breathe. Water that is continually moving or flowing inhibits mosquito populations.
Look around your home and landscape for these possible sites of still water that can be excellent mosquito breeding grounds:
bird baths
potted plant saucers
pet dishes
old tires
ponds
roof gutters
tarps over boats or recreational vehicles
rain barrels (screen mesh over the opening will prevent females from laying their eggs)
bromeliads (they hold water in their central cup or leaf axils)
any other structure that will hold even a small amount of water (I even had them on a heating mat in a greenhouse that had very shallow puddles of water!)
You may want to rid yourself of some of these sources of standing water or empty them every three to four days. What if you have bromeliads, a pond or some other standing water and you want to keep them and yet control mosquitoes? There is an environmentally responsible solution. Some bacteria, Bacillus thuringiensis ssp. israelensis or Bacillus sphaericus, only infects mosquitoes and other close relatives like gnats and blackflies and is harmless to all other organisms. Look for products on the market that contain this bacteria.
Are you plagued with mosquitoes in your yard? Does it seem like you have a greater infestation than your neighbors? There may be some solutions to solve the problem other than using pesticides that negatively impact beneficial insects in your landscape.
Asian tiger mosquito. Photo credit: Susan Ellis, Bugwood.org.
Mosquitoes are not only annoying, they can transmit serious diseases such as: eastern equine encephalitis, dengue fever, dog or cat heartworm, chikungunya, malaria, St. Louis encephalitis and west Nile virus.
Let’s first explore what kind of environment in your landscape and around your home is friendly to the proliferation of mosquitos. Adult mosquitoes lay their eggs on or very near water that is still or stagnant. That is because the larvae live in the water but have to come to the surface regularly to breeze. The small delicate larvae need the water surface to be still in order to surface and breathe. Water that is continually moving or flowing inhibits mosquito populations.
Look around your home and landscape for these possible sites of still water that can be excellent mosquito breeding grounds:
bird baths
potted plant saucers
pet dishes
old tires
ponds
roof gutters
tarps over boats or recreational vehicles
rain barrels (screen mesh over the opening will prevent females from laying their eggs)
any other structure that will hold even a small amount of water (I even had them on a heating mat in a greenhouse that had very shallow puddles of water!)
Mosquito larvae. Photo credit: Ari Farajollahi, Bugwood.org.
You may want to rid yourself of some of these sources of standing water or empty them every three to four days. What if you have bromeliads, a pond or some other standing water and you want to keep them and yet control mosquitoes? There is an environmentally responsible solution. Some bacteria, Bacillus thuringiensis ssp. israelensis or Bacillus sphaericus, only infects mosquitoes and other close relatives like gnats and blackflies and is harmless to all other organisms. Look for products on the market that contain this bacteria.
