Beating the buzzers
Locals offer tips on battling mosquitoes with bats, birds, bacteria and more
Wednesday, Jun 25, 2014 06:00 am
It’s summer. It’s when we all prefer to be out in the sunshine, doing our gardening, going for a jog, lying on the beach…
Slap! Slap! SLAP-SLAP-SLAP! AAAARGH… MOSQUITOES!!!!!
There are 41 species of mosquito in Alberta. Aedes vexans is the most pestiferous one and is more common during June and July, as is A. dorsalis. A. spencerii is the ankle-biter that often comes out early in the spring. These are the two that are most common around St. Albert.
Spring is the same time we see Culiseta inornata, the Godzilla-sized species that appears around the province the earliest after winter.
There’s also C. tarsalis, which is most abundant in July and August. That’s the one that is notable for its ability to transmit West Nile virus but public works officials say it’s rarely seen around these parts.
There’s no escape from any of the pesky bloodsuckers but word is that there are things that you can do to stop them before or after they become airborne.
Bats, man …
The city’s public works department offered people the chance to make their own bat houses during its annual open house a month ago. It’s a new program that the department hopes will offer not only a boost to the province’s flagging bat numbers but also a bane to the mosquito squadrons that sometimes take over open parks and backyard spaces.
At the same time, officials are hoping that people will conduct their own informal surveys so they can track whether or not the little brown bats get more plentiful and the mosquitoes less so. City staff gave out 100 of these kits for the bat houses, approximately 30 of which were registered so that people could submit information back to public works for its observational program.
“It’s more anecdotal: ‘How many bats you’ve got? Have you seen them?’” said Tony Lake, the department’s manager of operations. “The scientific aspect of it isn’t that well designed but we do have registered bat house owners and reasonably spread throughout the city.”
This is much like an upcoming program set to take place in mid-July in Morinville.
“Bats should not be feared, but celebrated because they can devour more than 600 mosquitoes in a single hour!” exclaims the promotional information for the event. Although registration is already full, there is a waiting list. People can learn more about the event by emailing firstname.lastname@example.org.
Lake offered further written information that explained that St. Albert typically gets two mosquito hatches each summer, the intensity of each directly related to the city’s general moisture levels.
Mosquito larvae love small, temporary and stagnant bodies of water like puddles, open rain barrels or old tires. Apart from the bat houses, there’s not much else that the city does to promote the eradication of the pests.
“Spraying for mosquito populations was discontinued two decades ago as it impacted many beneficial insects such as bees and dragonflies,” the provided information reads. “The City of St. Albert did a pilot using a bacteria-based granule, similar to City of Edmonton but found that it is not effective. We are, however, lucky to have multiple mosquito predators around our city like dragonflies, bats and birds that help keep the mosquito populations down.”
There are lots of blueprints available freely online demonstrating how people can build their own bat house. Once constructed, each house should ideally be installed in a warm, sunny location that is out of the wind. It should be south facing and between five to seven metres off the ground.
That website also offers more helpful information on bats, including a data report form that feeds data to the province’s bat house program much like the one in St. Albert.
Bugs against bugs
Mike Jenkins graduated out of St. Albert’s schools and is now the biological sciences technician with the City of Edmonton. He enjoys being called the “bug guy” as he is heavily involved with that city’s mosquito control program. He is very familiar with VectoBac, that aqueous suspension formulation of Bacillus thuringiensis (subspecies israelensis), the bacteria-based granule that Tony Lake referred to.
He suggested that the bat house promotion probably wouldn’t do much. Bats, for one thing, don’t only eat mosquitoes.
“They actually prefer a big juicy moth or a beetle over a scrawny little mosquito,” Jenkins said.
Besides that, the bat houses have to be close enough to a body of water and positioned according to exacting standards before bats would even consider moving in. Our little brown bats have what he calls “high roost fidelity” meaning they’ll stick to wherever they’ve always called home unless something prevents that. People have no control over that.
“The good news is once they find that bat box and they’ve moved in, they’ll keep coming back over and over again.”
A week or two ago Jenkins was able to rest as Edmonton wound down another series of treatments with the Bacillus. As more rainfall comes along to fill up those puddles and old tires, he will come along with the bacteria or other products to combat the skeeters.
He said that Edmonton uses an aerial “broad spectrum” pesticide called Dursban 2.5G during spring. Its active ingredient is chlorpyrifos, an organophosphate that is considered to be moderately toxic. According to an Edmonton parks department report from 2011, this is the last summer that Dursban will be used, as it is no longer being manufactured. The Environmental Protection Agency in the United States banned it in 2001.
Jenkins also monitors the mosquito traps around Edmonton, just to see how populations rise or dwindle.
“We do find that St. Albert numbers are slightly higher than Edmonton, which makes sense because it’s outside of our control area,” he said.
In general, however, the numbers are “quite low, largely because we’ve had cold temperatures and raining conditions have kept down the number of mosquitoes actually flying around. It’s probably not really indicative of the actual mosquito population itself.”
This area’s prolonged winter did much to stave off the onslaught of winged intruders, which usually start to appear in late April to early May.
“It definitely delayed the development of our spring crop of mosquitoes, and helped us get after those mosquitoes and treat that population before a lot of them actually were able to emerge,” Jenkins said. “Our (first) mosquito came several weeks later than we usually get it. It certainly helped out for the first part of the spring here. The weather was all cool and horrible so nobody wanted to be out anyhow, except for the mosquitoes.”
People can learn more about mosquito control tips through the City of Edmonton’s information web page at www.Edmonton.ca/mosquito.
He added that attracting purple martins might be another way of helping out the cause, but those birds are not common around here. Besides that, they prefer larger bugs just like the bats do, they’re mostly active during the day whereas mosquitoes are primarily active during dawn and dusk. They really don’t interact in their activity cycles, he said.
They might also be counterproductive since they eat dragonflies, an insect that is a voracious predator of mosquitoes.
“We’ve often gotten questions why we don’t raise dragonflies and release them. They’re actually really difficult to rear in captivity. It takes two to three years for them to develop as aquatic larvae before they emerge and so they need a permanent body of water. They’re carnivorous so you need to feed them live food. They’re also cannibalistic so you can’t keep them together. It gets really, really complicated.”
Eastern phoebes and swallows are two other bird species that are known mosquito eaters.
Edmonton, Jenkins added, focuses instead on conserving and developing habitats like wetlands and permanent lakes or ponds to help foster dragonfly births. Newer stormwater facilities often include a naturalized wetland function. These, he said, often become great dragonfly habitats.
Plants against bugs
Jim Hole is also pretty knowledgeable about pest control. During his weekly Coffee and Questions with Jim on Saturday morning at the Enjoy Centre, I asked him if he knew of any plants that were tried and true mosquito repellents.
Not so fast, he says.
“It doesn’t exist, no matter how many times somebody writes about that or says it. It’s not going to happen. I’ve seen mosquitoes landing on citronella so my faith in that is pretty not so great. If you crush the citronella plant and rub it on your skin, it’ll give you some protection from mosquitoes for 15 to 20 minutes sitting on your deck,” he suggested.
Jenkins too balked at the notion of plants that naturally repel the blood-sucking critters. He mentioned a scientific study that looked at a citronella plant and a fake plant that looked like citronella.
“They actually found that the mosquitoes landed on the real plant more often than they did the fake one.”
So much for that.
Other plants that are rumoured to help in the fight include lemon balm, catnip, and lemon gem marigold. There’s also lemongrass, ageratum “artist purple,” and lemon thyme. Nothing is conclusive with any of them. The carnivorous Venus flytraps unfortunately won’t do much either. They’re an indoor plant, Hole said.
He did suggest Mosquito Dunk, the home version of the Bacillus anti-mosquito larva agent that Holes now carries.
“You just throw it in the water. It’s not going to attack the adult mosquitoes but it kills off the larvae. If you’ve got freestanding water, if you’ve got a pond, something collecting water, you throw it in there.”
Other home remedies like mosquito coils offer some help but Hole noted that they contain an insecticide that is marketed as a repellent. There is no such thing as the end-all, be-all mosquito protection.
“If there was something really great, we’d have it here,” he said.
What else is there?
Eating more garlic and drinking less beer are meant to help make the human body less palatable to mosquitoes. Wear light clothing, some people say. Use lavender oil or tea tree oil to offer some protection.
Kevin Veenstra, public works’ tree and pest team leader, said emptying standing water is the best preventative measure.
“Wherever you have standing water, that’s where you get the mosquito larvae developing,” he said.
Cleaning eaves troughs also helps.
Another trick he picked up from a co-worker: “Just set up an oscillating fan. Mosquitoes … they don’t like wind.”
Apart from that advice, Garden Bugs of Alberta: Gardening to Attract, Repel and Control (2008, Lone Pine Publishing) had another idea or two. Start by keeping your lawn cut short and remove thick vegetation, as it provides a resting site for mosquitoes. Doing this, and removing birdbaths or rain barrels, leaves little for the skeeters to enjoy.
“Now, I have just described the ideal mosquito-free yard – a barren wasteland,” write authors Ken Fry, Doug Macaulay and Don Williamson.
“Instead of this extreme, you could use repellent and long-sleeved clothing. We take for granted having screens on our windows and doors – why not go one step further and wear mosquito-netting clothing?”