Western tent caterpillars are camping out in droves in city parks and public places to feed their voracious appetites for leafy destruction but the pesky critters have nothing to fear from city parks staff, who will not be spraying pesticides to halt the wormy advance.
"We don't spray in any public places, just because it's hard to keep the public away and do it safely," said Flavio Viola, the city's manager of parks and solid waste.
While there is no formal ban on pesticide use, Viola said for the past five years it's been the city's policy not to spray for pests. However, the mosquito abatement program still exists and crews from the Integrated Pest Management division have been active applying Aquabac, which contains BTK, a naturally-occurring bacterium that works to destroy the digestive system of mosquitoes.
That use of Aquabac has been suggested by local gardening expert Jos Van Hage to kill the caterpillars, but Viola said even though it is an organic substance, BTK spraying still poses risks to small children, pets and people with breathing problems like asthma. The substance would have to be reapplied in seven to 10 days and it might require several applications.
"Obviously, spraying by plane in not an option, and the only other way would be to spray it from the top using a bucket truck," said Viola. "Trying to do all the downtown trees and city boulevard trees to try to control these caterpillars would be very costly. The only budget we have right now is to deal with nuisance mosquitoes, which council approved a few year back. But we don't have any budget to deal with the caterpillars. Our first priority is the safety of the public, and that's the main reason."
In Monday's Citizen, Myrna Kewin, a downtown store employee, stated the poplar trees now under attack by caterpillars on Third Avenue were replaced last year when their predecessors died due to a lack of water. Viola said those trees (15 of them) were actually replaced after being broken by humans.
"That area is really bad," said Viola. "There's a [drinking] establishment that's open late at night and they come out intoxicated and like to do things to the trees on Third Avenue. Those trees are watered every day. [The destruction] was mostly from vandalism."
Following last summer's moth invasion, this is an especially bad year for tent caterpillars, which are targeting aspen poplars, mayday and choke cherry bushes all over the city.
Unlike some B.C. cities, like Victoria, Saanich and Surrey, which have outright bans on pesticide uses for cosmetic purposes, there is no such prohibition in Prince George, but strict provincial regulations do apply. While Viola admits some of the trees being attacked will be more vulnerable to winter kill, the city's policy against spraying takes precedent.
"We try not to use any type of herbicides or pesticides," he said. "Even the weeds on the boulevards, we use propane torches to try to burn them off rather than spraying them with chemicals. That's the last thing we want to do. You have to put up signs and block the area all off so the public can't get around there for 48 hours.
"The caterpillars do stress the trees, but they won't kill all the trees."
Claire Watkins, the Integrated Pest Management co-ordinator, said the problem is cyclical and the caterpillars won't likely have longterm adverse effects on healthy trees, even after repeated attacks. Some city residents are fighting the spread by using the pesticide malathion, or by painting tree trunks with a sticky substance known by the trade name, Tree Tanglefoot, or with a band of axle grease.
"When it comes to using pesticides on public land, we are heavily regulated, and what people can do on private property is way different from what we can do," said Watkins. "For us, pesticide labels are the law, and pretty much everything we checked into using for the tent caterpillars said not to use them in public places where there's a possibility of human contact. With the trees downtown, if caterpillars are going to stick to the trees, so will people."
