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Climate and Environment

Bugs Bugging You? Coyotes Got You Howling? We've Got Tips On Warding Off Nature's Peskiest Critters

A close up of an Aedes mosquito, which appears to be black with small white spots, on skin.
The Aedes mosquito can transmit diseases such as Chikungunya, Dengue, and Zika.
(Courtesy of the National Institute of Allergy and Infectious Diseases
Creative Commons via Flickr)
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Springtime is about a month away, and summer will be here before we know it. In Los Angeles, both seasons invite people to enjoy the great outdoors and bask in the sun. Summertime brings those warm summer nights.

Which bring bugs, and all kinds of other critters and wildlife. In the spring, you might see more coyotes — mating season means they’ll be hunting more. Owners of cats and tiny dogs beware! Urban coyotes are pros at surviving, especially when they have more mouths to feed.

Warmer months mean mosquito season, and yet again trying to find ways to prevent getting those itchy bug bites.

So, how does one ward off unwanted house guests?

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Who We Spoke To
    • Michael Beran, owner, Wildlife Command Center in St. Louis
    • Anandasankar Ray, molecular cell and systems biology professor, University of California, Riverside

Mosquitoes and other flying pests

There are more than 3,500 species of mosquitoes, but only about 20 bite humans, according to Anandasankar Ray, a molecular cell and systems biology professor at the University of California at Riverside.

Another fun fact: only female mosquitoes bite.

Over the last two to three years, as my colleague Caitlin Hernandez has covered, Southern California has experienced a growing problem with mosquitoes. Ray says that’s because there are two new species of mosquitoes breeding and spreading in the region: Aedes aegypti and Aedes albopictus.

The Aedes mosquitoes, or “ankle-biters,” are day-biting mosquitoes.The invasive Aedes species began populating Southern California in 2011 and have the potential to transmit viruses such as dengue, chikungunya, zika and yellow fever.

The night-biters are Culix mosquitoes, and they can transmit the West Nile virus. But no need to be alarmed (right now) as none of these viruses are currently known to spread within the state, according to the California Department of Public Health.

Watch out for standing water. Ray suggests a preventative approach beginning with identifying areas around your home and community where water accumulates, like in flower pots, rain ditches and backyard drains. That’s the first step. Mosquitoes lay their eggs in stagnant pools of water, no matter how big or small — even up-turned bottle caps filled with water can become a mini-cesspool for mosquito larvae to thrive.

The second step is to use a larvicide. Bacterial larvicides are made from natural substances and is toxic to mosquito larvae, black flies and fungus gnats, according to the Centers for Disease Control and Prevention.

Don’t rely on citronella. Unfortunately, citronella is not very effective at repelling mosquitoes, according to Ray. Citronella tiki torches are poorly effective because they aren’t used in closed spaces and are usually placed on a yard’s periphery, so the citronella-infused smoke blows away with the wind. Ray says citronella candles are a bit more effective in repelling mosquitoes but only in the immediate area where it is placed. “Test after test after test, they don’t seem to hold up to the same level of protection as say, the insecticide-based chemicals do,” said Ray.

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Repellents can work. The most common and arguably effective chemical found in insect repellents is deet. The chemical was developed by the U.S. army in 1946 and was registered for public use in 1957. According to the most recent review by the EPA in 2014, deet continues to meet safety standards and is not identified as a concern to human health, as long as people the instructions for applying it. Deet also breaks down easily, so its usage isn’t an environmental hazard.

If you want a plant-based alternative to deet, oil of lemon eucalyptus (OLE) is an effective insect repellent — and note that OLE is different from lemon eucalyptus essential oils. Ray says OLE is as effective as the commonly used deet-based products. The main component of OLE containing its insect repelling chemical is p-Methane-3,8-diol, or PMD, and that chemical can be more effective than deet at repelling ticks Popular brands include Cutter, Repel, and Natrapel. Just make sure not to get it, or any other bug repellent, in your eyes!


A 2016 study by the Journal of Arthropod-Borne Diseases found oregano oil to be an effective repellent against the common brown-banded cockroach. The study also found eucalyptus, mint, yarrow, and rosemary essential oils to be effective in surface treatment or fumigation against that species of cockroach.


A 2017 study by the Entomological Society of America found that female spiders are repelled by chestnuts and peppermint oil. As for male spiders and other pesky insect pests, sticky traps and lures are effective tools available to purchase at hardware stores. The strong smell of peppermint oil diluted with water can also repel mice and rats.


To ward off female raccoons looking for a nook to nest their young in, Michael Beran, the owner of Wildlife Command Center in St. Louis, suggests using Raccoon Eviction Fluid. It’s designed to smell like a male raccoon, which are predators to female raccoons during birthing season.

Playing a soundtrack of large predators (bears, dogs, etc.) was found to be an effective way of keeping away raccoons, according to a 2016 study published in the Journal of Nature Communications. Of course, if you actually have a large dog that barks, that could work too.

Worth noting: One of the raccoon's few local predators is the mountain lion.


Sometimes, the best repellent is physics. Coyote rollers are fencing tools “where you take the existing fencing that is in place and you put these rollers, these long four foot rollers at the top of the fence, and so coyotes try to jump up on the fence to go over and it rolls,” Beran said.

He’s found coyote rollers to be the most effective tool to keep coyotes out of a yard, farm or other fenced area. The rollers use the animals body weight to roll them back off, and it doesn’t work for smaller critters like squirrels or raccoons.

Learn More About Coyotes
  • January through March is coyote mating season in Los Angeles. Read up on how to get along with one of L.A.'s cutest little predators in our L.A. Explained guide.

Coyotes may respond to some predator smells, but … that route is icky. Members of the canine family are famously known to mark their territory with urine. An LAist reader asked us: Can wolf urine ward off coyotes? And the simple answer is no, at least in environments where there aren’t any wolves, such as Los Angeles.

“If a coyote was attacked by a wolf and the coyote survived, that coyote would teach all of its offspring and its pack mates that wolves were dangerous,” Beran said.

But coyotes in Los Angeles don’t know to be scared of wolves, or their urine, because they’ve never encountered them.

“Wolves have been out of the system for so long that coyotes aren't afraid of them. How would they even know to be afraid?” Beran said. He added that there must be a bridged behavior for a scent to work on anything.

One of the few common predators of coyotes is ... us. And if you ask the internet about using human urine as a deterrent, you'll see all kinds of answers. But there's not actually any science to back it up, and also ... maybe just try the rollers?

Use of sound

Some people try ultrasonic devices to ward off the small mammals that plague your backyard vegetables. Do they actually work? Another simple answer: in the long run, no.

“What we find all the time is they work really good for the first week and then they work less, and then they work less, and then they don't work at all,” Beran said.

Can animals hear ultrasonic noises and are certain frequencies bothersome to animals? Yes, however, “this sound, even though we're cautious and aware of it, isn't really producing any harmful effects. So we're just gonna press through to survive,” Beran said about animals.

“Food, water and shelter are such driving primal forces that animals press against that constantly until they recognize that there's no threat and that it's safe and that they can move through there. And so that's why a lot of these devices, a lot of these home remedies don't work, you know?” Beran said.

Don't trap

California has some of the strictest trapping laws in the country. Governor Gavin Newsom signed the Wildlife Protection Act of 2019 that bans commercial and recreational fur trapping.

What questions do you have about Southern California?

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