A tank full of these little glittery fish is the first thing you see upon entering the front door of the Environmental Health building on Hazard Way. The little surface-breathing Gambusia affinis are found naturally in the county, and Dice has fish traps in the back of her truck to catch them whenever possible. “If I’m at a site that has some, then I’ll set a trap there and head back at the end of the day to take them back to the office. They’re hard workers, and they work cheap,” she jokes. “They don’t have a union.”
Dice dips her golf-club ladle into the edge of the swollen area of Rose Canyon Creek, lets some water eddy in, and then lifts the ladle toward her face, looking for larvae. She dumps the water and checks twice more at different spots along the edge. “I’m not finding any larvae here,” she says. “And that’s a good thing. That’s encouraging.”
Dice and the other technicians in her department have been pushing themselves to hit as many potential breeding sites as possible, as often as possible. They drive around all day in their white Ford Ranger trucks.
But helicopter drops are also used to get to places that are unreachable from the ground, such as large standing ponds socked in by thick vegetation. Every three weeks during the height of the mosquito-breeding season, from June through September, the Department of Health’s single helicopter will head into the air.
“We use it where we need it,” Dice says of the helicopter, noting that each time it goes up, it costs the county taxpayers about $5000. “But, by golly, if you can squeeze in there and get the job done, then you should squeeze in there and get the job done.”
But many of the mosquitoes in the area come from places much closer to home, even “small sources in our own backyards,” Dice says. “A watering can that you’ve forgotten about, or plant saucers. Without some knowledge about it, you’d have no idea to look there for mosquitoes. A lot of people have no idea that mosquitoes have an aquatic larval stage before they progress to adults.”
Joggers and dog-walkers pass by periodically in the Rose Canyon morning light. After a few more stops along the path, checking with her golf club ladle, Dice determines that the park is clean. “I used to have to hike entire canyons through thick brush,” Dice says. “But now I can mentally trim areas down to their standing water and just pull up at specific spots.”
She climbs back into her truck and drives out to Genesee Avenue, heading toward Pacific Beach. “I have some street gutters holding water in Pacific Beach, near the military housing behind Mission Bay High School. “It’s an area I watch pretty closely, because we’ve had a higher rate of bird mortalities there lately.”
Dice has a host of weapons in her arsenal when mosquitoes are discovered.
In the back of her truck, along with the golf-club ladle and wire-mesh traps for catching mosquito-eating fish, Dice has an old-style B&G tank of Golden Bear Oil, a powerful pesticide that she hates to use. “It’s the only thing that will kill pupae,” she says. “It’s a suffocant. It lays on the surface of the water. It’s a short-lived product, but while it’s there, it kills all the other aquatic insects at a site. It’s very sad because I particularly like dragonflies and damselflies.”
But Dice hardly ever resorts to using the Golden Bear Oil. She has much safer products locked inside a large, black, rubber trunk in the back of her truck. It just so happens that this trunk is covered with multiple images of skulls and crossbones.
“It’s just the law that we mark it that way. But there’s no poison in there. It’s just full of Bti and growth inhibitor.” Bti stands for Bacillus thuringiensis israelensis. It refers to any bacterial product that controls pests.
Dice explains, “Originally, it was a mosquito product that was discovered in Israel in the early ’80s. One year, they went out to control the mosquito larvae, and there were none. And they noticed that the leaves on the corn plants had developed some type of problem, and they were dropping off into the water. And corn plants don’t normally drop their leaves. So they looked closer, and they found a particular bacteria that affects only the gut of mosquito larvae. So now when I put VectoLex or another Bti product out into the water, I feel good about it, because I know it’s only going to affect the mosquito larvae. If a coyote wants to come by five minutes later and have a drink of water, it’s not going to affect him.”
VectoLex is ground-up corncob impregnated with bacteria specific to the gut of mosquito larvae.
Dice remembers testing the first Bti’s 25 years ago, and after she sprinkled some in a pond, a flock of ducks flew down and ate it up just as fast as she could spread it out. “At first I thought, ‘Oh, no!?f I was used to pesticides, and here these ducks were eating this stuff.”
The ducks were pets, and they were subsequently observed for adverse effects. “They were fine,” says Dice. “And after that, I felt relieved to have this product. Not to mention, but 24 hours later we came back, and there wasn’t a single mosquito larva living.”
Thanks to the successful development of Bti’s, the county hasn’t sprayed pesticides in over 16 years, according to Dice.
Another weapon in Dice’s arsenal is a growth-inhibiting hormone called Methoprene. This slow-acting insecticide prevents eggs and larvae from developing into adults, so that the mosquitoes die in arrested stages of immaturity. Methoprene has no effect on adult mosquitoes, however.
“Methoprene works long-term,” says Dice. “And if you’re regulating sensitive areas, or areas that are difficult to get to, you want to use a long-term product.”
GETTING TO KNOW YOUR “BUGS”