Fort Collins – Flies have an old family joke: They’re annoying, but they get your blood.
Mosquito season has started again in most of the United States. And that means biting the bug.
When a fly bites you, it pierces the skin with a mouthpiece called a proboscis to suck blood. When eaten, it injects saliva into your skin, which can cause a reaction – swelling and itching. But pests can also spread parasites like malaria and viruses like dengue, West Nile and Zika.
So, you might want to pause your summer vacation planning and consider what to look for in an insecticide that keeps bugs away and kills them.
MOSQUITOES ARE THERE ANYTHING?
The Centers for Disease Control and Prevention says people should look for these active ingredients: DEET, IR3535, picaridin or oil of lemon eucalyptus for protection that lasts several hours. The substances are registered with the Environmental Protection Agency.
A note about lemon eucalyptus oil: Lemon eucalyptus essential oil has a similar name, but the FDA does not recommend it because it has not been tested and is not EPA-registered as an insect repellent.
Likewise, the CDC does not endorse other “natural” products that have not been evaluated.
Gloves are one way to protect yourself from insects, but there is another: Wear long sleeves and long pants. Avoid going out at dusk and dawn, when some types of flies are most active.
Sylvie Huijben, an evolutionary biologist at Arizona State University, helps children learn how to protect themselves from mosquitoes by playing online games that emphasize other prevention strategies:
“Flies need water to breed,” so it’s important to avoid standing water, including buckets of water or kiddie pools left in the yard for a week or more. “Make sure you’re not contributing to the mosquito problem and you’re not breeding mosquitoes on your property.”
You can also treat clothing and outdoor equipment with permethrin pesticide to repel flies and other unwanted pests.
INSECTICIDES NOT TESTED
The Centers for Disease Control and Prevention is working with a mosquito laboratory in Fort Collins, Colorado, where it is evaluating insecticides, but not repellents.
To test this type of product, researchers cover the inside of the bottle with a specific dose of insecticide, then put flies in the bottle – usually about 25. They see how many bugs die in two hours and compare it to a closed bottle containing the same number of flies.
This test is widely used in the United States and is increasingly being used around the world. It is considered simpler and cheaper than some more complicated alternatives, including testing insecticide drops directly on flies.
CDC officials say scientists repeat the experiment each season to change how mosquitoes respond to insecticides.
Huijben said it’s important to repeat the test because it has limitations: The results can be thrown off by factors such as whether or not each bottle is coated with a chemical.
“I think we hear a lot of noise in the data,” which can lead to false positives, said Huijben, who compared resistance testing methods.
Are mosquitoes resistant to chemicals?
Just as bacteria can gradually develop the ability to destroy antibiotics, bugs can develop resistance to certain chemicals designed to kill and destroy them.
Permethrin belongs to a group of insecticides called pyrethroids that show similar resistance.
Pyrethroids gained popularity in the 1990s as a replacement for older pesticides and are often used to control adult pests.
Pest control programs and farmers use chemicals, but homeowners can also find them on hardware store shelves.
In laboratory tests, resistance varies by product and dose, but in some tests, “none of the (flies) died,” CDC entomologist Roxanne Connelly said.
CDC officials are working with state and local officials to conduct more real-world tests, including tests in which flies placed in open fields are tested after trucks with insecticides pass by.
