Integrated Pest Management (IPM) is a science-based pest management process which focuses on managing the ecosystem for the long-term prevention of pests and the damage they cause.  The University of California Division of Agriculture and Natural Resources (UCANR) has developed an IPM program dedicated to helping Californians “prevent and solve pest problems with the least unintended impacts on people and their environment.”  For the home gardener, a guiding principle of IPM is to understand why your landscape favors particular pests, and then enact changes which will make that environment less attractive to those pests. 

One component of the IPM approach is to use biological control measures rather than pesticides to curtail garden pests whenever possible.  This usually involves creating conditions that attract the natural enemies of pests.  For rodent control, owls are an often-overlooked ally of both home gardeners and farmers.

According to the Altacal chapter of the Audubon Society, ten different species of owls can be found in Butte County.  Of these, eight are permanent residents: Barn Owls, Great Horned Owls, Western Screech Owls, Northern Pygmy Owls, Burrowing Owls, Spotted Owls, Long-eared Owls, and Short-eared Owls.  Since most owls are nocturnal, they aren't easily seen in the wild, but birders often recognize different species by their distinctive calls.  [The National Audubon Society has a website with recordings of the calls of different bird species, including owls].  I've never seen them, but I regularly hear Great Horned Owls and Screech Owls around my home in the foothills above Oroville.

ll animals have three basic needs: food, water, and shelter.  In the case of owls, their food (primarily rodents) is already present in most environments, whether wildland, rural, suburban, or urban.  Owls also get the water they need from their prey.  Providing shelter is the one thing a property owner can realistically do to attract owls as a method of controlling rodent pests.  Shelter for most owls consists of rotted hollows in trees or artificial nest platforms and nest boxes.

Nest boxes are commercially available but can be expensive.  For the DIYer, nest box plans for various owl species are available at no charge from the Cornell Lab of Ornithology.  Either the roof or one side of a nest box should be hinged to create a door that can be opened for cleaning after any owlets have fledged and left the nest.  Quarter to half-inch holes drilled near the roof will aid air circulation and similar holes in the floor will allow drainage if necessary.  Lay wood chips or wood shavings on the floor of the box for bedding.  The box should be placed at least 15-20 feet above the ground with the opening facing northeast.

Owls regurgitate the undigested fur and bones from their prey in the form of pellets.  Pellets and fecal material will build up inside the nest box, so owl boxes need to be cleaned out at least once per year, after their occupants have vacated.  The best time to clean boxes is October to December.  Be sure to avoid breathing the unhealthy dust when cleaning a nest box.

Owl safety is a consideration when deciding if it is appropriate for you to attract them to your property.  Do you have high speed roadways nearby where owls could collide with vehicles?  Do you or nearby property owners regularly use pesticides, herbicides, or other potentially harmful chemicals?  As predators, owls are particularly susceptible to such chemicals as they often become more concentrated as they pass up the food chain.  Additionally, the light pollution produced by porch and outdoor lights can be confusing and act as deterrents to these nighttime hunters. 

It is important to preserve large trees because most owls prefer mature trees for roosting, hunting, and nesting.  Dead snags can provide nesting cavities but can be hazardous in fire areas. Finally, think about family pets.  A hungry owl could make a meal of a small dog or house cat.  (I have a sneaking suspicion Great Horned Owls are the reason our local feral cat population has been kept in check).

The natural habitat preference of a particular owl species will help guide the decision on which species to attract.  Four owl species found in Butte County with varying habitat needs are good examples of how habitat influences owl distribution: Barn Owls, Great Horned Owls, Burrowing Owls, and Western Screech Owls.

When Humboldt State University graduate student Carrie Wendt studied Barn Owl nest site preferences, she found that they preferred nest boxes near grassland, riparian, and mixed forest habitats as opposed to mixed scrub.  Therefore, efforts to attract Barn Owls to heavily wooded areas are likely to fail. 

Barn Owls are medium-sized owls, with adults standing 13 to 16 inches tall and weighing between one and one and a half pounds.  They usually hunt within one to three miles of their roost and are only mildly territorial, so you can put up several nest boxes in an area with possibly multiple families taking up residence.  Great Horned Owls are the fiercest predators of Barn Owls, while collisions with cars also contribute heavily to the Barn Owl death toll.

Barn Owls seem to be the go-to owl when it comes to biological control of rodent pests, dominating the literature on owls and IPM.  According to several studies, pocket gophers, mice, and voles constitute most of the Barn Owl diet.  In fact, 99.5% of prey creatures studied were agriculture pests, so clearly owls can provide valuable pest control services for farmers.  According to UCANR, a family of five Barn Owls, including two adults and three young, will feed on about 1,000 rodents during a season.  Because they prefer to hunt in more open areas, they readily hunt in vineyards, alfalfa fields, and along levees, making them valuable allies for farmers practicing IPM.  Over a three-year period, one study found that Barn Owls killed more than 30,000 rodents in a single vineyard for a fraction of the cost of trapping or poisoning: “the average cost of trapping was $8.11 per pocket gopher versus $0.34 per rodent taken by Barn Owls.”

On the other hand, Great Horned Owls prefer to nest in wooded areas with scattered clearings.  In nature, they will nest in old hawk, magpie, raven, and crow nests, so they are more likely to be attracted to an artificial nesting platform or nest basket rather than a nesting box. 

Growing up to two feet tall, weighing three pounds, and with a wingspan of nearly four feet, this huge, powerful bird is the largest owl in North America.  It gets its name from tufts of feathers (“horns”) projecting from its head.  Fierce predators, they will hunt prey weighing up to 15 pounds, including rabbits, grouse, and skunks (and family pets!), as well as smaller prey such as squirrels and mice.  Great Horned Owls will hunt and kill all other owls, so don't place Great Horned Owl nest baskets near any other owl boxes.

Burrowing Owls have historically preferred nesting in prairies and grasslands -- areas with short grass or exposed soil where they can excavate their burrows.  Today they can also be found on farms, golf courses, vacant lots, and even airports.  Unlike other owls, Burrowing Owls nest in underground burrows and these sorts of open spaces facilitate burrow construction.  These owls will often commandeer and enlarge burrows started by other animals.  Property owners who can offer this kind of habitat can further encourage Burrowing Owls to take up residence by starting an artificial burrow that these owls can complete.

Once called “howdy birds” by cowboys due to the rhythmic head nods they make from inside their burrow entrances, these smaller owls reach a height of only nine inches and weigh just seven ounces.  Burrowing Owls feed on small birds, reptiles, large insects, rodents and even fish.  Although they do some hunting at night, Burrowing Owls are diurnal, meaning they are active during the day, an uncommon pattern for an owl. 

Another small owl, the Western Screech Owl ranges in size from seven to ten inches tall and weighs between three and a half and eleven ounces.  Western Screech Owls have a wide-ranging diet that includes everything from worms and crayfish to rats and bats.  They will even take prey larger than themselves, such as cottontail rabbits or mallard ducks.  Although they are gutsy hunters, if they are frightened these masters of camouflage will elongate their body and tighten their feathers so that they appear to be a branch stub. 

The natural habitat of Western Screech Owls is open woodlands, where they nest in tree cavities, but they can also be found in urban parks and residential areas.  Because they will readily occupy backyard nest boxes, they are probably the most likely owl candidate for a suburban homeowner to entice into their yard.   

Owls can be a valuable ally for farmers and homeowners who wish to practice biological pest control. With a little research and relatively minimal effort they can be encouraged to take up residence near you.

Want to learn more about Integrated Pest Management? Attend our free workshop on October 15^th, part of the Master Gardeners' Fall 2024 Workshop Series.  For more information visit our website.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

It's an exasperating experience. You go to the nursery, pick out a flowering plant, shrub, or tree and bring it home only to have some critter damage or destroy it within the first week. Pests cause damage and waste time and money. The most common pests in the home landscape and garden are voles, moles, and gophers. By knowing what you're dealing with, it will be easier to eradicate the problem.

Voles. Also referred to as field or meadow mice, voles are small rodents three to nine inches in size (depending upon the species).  They look a lot like hamsters, which are their close relatives. Damage done by voles is often mistaken for that of gophers. Voles are herbivores; they can gnaw on the bark of trees and shrubs, or simply eat the roots. They will also eat the tops of new vegetable transplants, leaving behind damage similar to deer nibbling. If you look closely, you'll see the vole's teeth marks on the stalk of the plant.

Voles are active both day and night and do not hibernate. They are shy creatures and build complex tunnels under dense ground cover such as lawns, grasses, and meadows. They live in colonies, spending most of their lives underground. Voles have an extremely short life cycle, living just three to six months, but females can become pregnant at three weeks old. The gestation period for female voles is sixteen to twenty-four days. A typical litter is five to eight baby voles. Young voles become self-sufficient after several days, at which time the mother vole moves on to find another partner to mate with. Because of their rapid reproductive rate, one mating vole pair can be responsible for producing one hundred voles (offspring, offspring of offspring, you get the picture) in a year. Even a single pair of voles can rapidly become a vole kingdom.

If you don't take measures to control voles when you first notice evidence of their presence, they can quickly create a problem that spirals out of control. Signs of vole infestation include holes with a surface diameter of around one and a half inches close to their surface runways (raised ground on top of their tunnels). Damage to the roots of trees, yellowed and wilting plants, missing bulbs, teeth marks around the bottom of trees and shrubs, and irregular paths of one to two inches of trampled grass or soil are also signs of vole infestation.

Modifying the habitat can be effective in controlling vole populations. Keeping the yard cleared of dense vegetation, any lawn mown, and shrub branches trimmed up off the ground can deter voles. Circling tree trunks with guard mesh is also helpful. Voles often thrive underneath weed cloth put down to prevent weeds from growing around ornamentals, and beneath mulch used to keep plant roots cool in the summer. Removing both is a deterrent tactic. It is also helpful to remove bird feeders, or control birdseed spillage. Keeping birdseed off the ground reduces food for voles.

Exclusion, repellants, and traps are more effective means of controlling voles. Hardware cloth (with one-quarter inch or smaller mesh) can be a useful barrier. The cloth can be fashioned into a fence at least twelve inches high and buried three inches in the ground to surround flower beds. Baskets can be made or purchased to protect trees and shrubs. Because coyote and fox urines are stressful to voles, application encourages them to move on. Coyote urine and fox urine can be purchased online. Repellants containing capsaicin (and active component of chili peppers) and thiram (a fungicide) have also proved to be effective on ornamental plants, but remember that repellants often wash away with rain and need to be reapplied. Although bait is not required, peanut butter mixed with oatmeal can be smeared on trap triggers when using mouse traps to eradicate voles. Two to three traps need to be set by each hole or runway. Baited traps need to be covered with a box or PVC pipe to deter other critters such as birds and squirrels. Make sure the box has a one-inch hole cut out in order to allow the vole to reach the trap.

Moles. While there is only a one-letter difference between moles and voles, that's where the similarities stop. Moles are five to seven inches long and have long, fleshy noses which serve as touch organs. The feet, nose, and tail of a mole are pink. Moles have no external ears. Their eyes are buried in their fur, and their broad front feet are equipped with super-sharp claws for digging. Moles are mammals, not rodents, eating worms, ants, and grubs (certain beetle larvae). Many people attempt to control moles by eliminating their food source, but this has proved to be a difficult strategy because of a mole's varied diet. Eliminating grubs in a lawn will only lead moles to turn to earthworms in garden beds. But earthworms are good for our soil and leave behind beneficial castings.  

Moles live entirely underground and can tunnel one foot per minute, creating extensive tunnels and volcanic-shaped mounds when breaking ground. A mole's damage to a lawn or plant is accidental since they, unlike voles, don't eat plants. Most of the time, a mole causes little damage other than an unsightly raised bed or a tunnel in the lawn. In a way, they're actually helpful critters as they aerate the soil. Moles produce one litter per year in the spring, and in four to eight weeks young moles reach adult size. They're active year-round but male moles are especially active in February and March when looking for a female, and females are most active in May and June when they are feeding their young.

Since modifying the environment means ridding the soil of beneficial insects and worms, the only effective way to completely eliminate moles is by trapping. Traps are readily available in hardware and big box stores. If you don't mind moles, but don't want them in specific areas of your garden, repellants may work. Castor oil is a common mole repellant, but its efficacy is disputed. Sonic repellants, both solar and battery operated, emit vibrations that may scare away moles. The frequency isn't audible to humans and isn't harmful to children, pets, and other wildlife.

Gophers. Like voles, pocket gophers are rodents and herbivores. They prefer the fleshy underside of plants and roots. Called pocket gophers because of their furry cheek pouches that carry food and nesting materials, these critters are larger than either moles or voles, ranging from six to ten inches long. Gophers have long, yellow-orange front teeth, small eyes and ears, and short tails.

Five gopher species live in California. The most common is Botta's pocket gopher, T. bottae. These pests create an extensive underground burrowing system. Feeding tunnels are usually six to twelve inches below the surface. Nesting and food storage tunnels can be as deep as six feet below the surface. Gopher mounds are crescent-, horseshoe-, or fan-shaped, with a hole that is off to the side and usually plugged. One gopher can create several mounds in a day. Sometimes a gopher can be seen pushing dirt from a mound or feeding at the edge of a mound. They don't hibernate, tunneling through soil all year long, day and night.

Gophers can wreak havoc on a row of plants by pulling entire plants down into their tunnels. They use their sense of smell to locate a source of food, preferring herbaceous plants, shrubs, and trees. Gophers will also gnaw on drip irrigation tubes and hoses.

Gophers reach sexual maturity at one year. Females produce up to three litters a year, with an average of five to six offspring per litter. Gophers live alone in their burrows except when females are caring for their young or during mating system. Since gophers can live up to three years, a gopher colony can become quite large over time.

As with moles, trapping is the most effective way to eradicate the problem of gopher infestation. Make sure children and pets stay away from the traps, because the traps can cause injury. Employing gopher baskets and mesh barriers is an effective alternative. While some roots will escape the barrier, the main roots near the base of a plant will be protected. Sonic repellants my also deter these rodents.

Voles, moles, and gophers can wreak havoc in the garden but they can be managed using various methods to control, deter, or eradicate. Consider your natural environment, whether children and pets can be harmed by deterrents, the expense of the deterrent method, and your commitment to the program of eradication when choosing a plan to deal with these pests.

For further information, see Kim Pokomy, Moles, voles and gophers dig the garden | OSU Extension Service (oregonstate.edu).

For in-person help in dealing with these critters (including a demonstration on exactly how to set a gopher trap), attend our free workshop on gophers, moles, and voles October 9^th, part of the Master Gardeners' Fall 2024 Workshop Series. For details, and to register, visit our website.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

Once again, we are experiencing a summer of devastating fires, with repercussions that will last decades or even longer. One of the lesser-known ways in which wildfires wreak havoc is the fact that they create ideal conditions for a particular pest, Melanophila acuminata, the black fire beetle. Also known as fire chasers or fire bugs, these beetles are often the very first to arrive at the scene of a conflagration. By using pheromones, chemical signals, and auditory cues, and monitoring temperature and humidity, Melanophila acuminata will fly over eighty miles to a freshly burned forest. Once there, they meet up, mate, and lay eggs, thriving in places most living creatures avoid.

These wood-boring shiny black beetles are 7-11 mm in length and rocket shaped, with stiff bristles on their under-bellies. They are found in Europe, the Caribbean, Central America, North America and South Asia. In addition to zeroing in on burn scars, they show up at lumber yards, sugar mills, tar plants, cement kilns and smelting plants, anywhere they can find hot pipes and equipment. Interestingly, in 1943 an article in the Journal of Economic Entomolgy noted that fire beetles sometimes swarmed in large numbers at football games in UC Berkeley's California Memorial Stadium, presumably attracted by the clouds of cigarette smoke that hung over the stadium during a big game.

Burning trees give off chemicals like ethanol which attract the beetles, too.  But why do they go towards the fire when everyone else is running away? According to the American Museum of Natural History news blog (Dec. 2017), burned areas are usually free of soil-dwelling enemies as well as birds that feed on larvae.

Once they have arrived at the scene of a fire, Melanophila acuminata use sucking mouthparts to ingest tree and plant fluids. Chemical cues from burned vegetation determine the optimum time and place for egg laying. Strong social bonding guides their nesting behavior, provides protection from enemies, aids in finding food, and helps them rear their young.

These crafty critters are able to withstand, extreme temperatures because they use a copper enzyme to create an exoskeleton, like a suit of armor, for strength and insulation from extraordinarily high temperatures.

As if firefighters didn't have enough to worry about, Melanophila acuminata bite. They often mistake a warm-blooded person for a warm burnt tree and try to burrow under the skin to lay eggs. Hundreds of these creatures will swarm and produce a very loud buzzing sound. Evacuees returning to their homes after a fire should be vigilant as these swarms are intimidating and their bites hurt. In fact, sometimes firefighters will wear bee veils for protection from the powerful stings. But the danger of beetle bites is, happily, short-lived: the swarms evaporate in a few days as the burned materials cool. 

The eggs, laid under the burned bark of trees, primarily conifers, cannot survive the repelling chemical defenses of healthy trees. Indeed, the eggs are sometimes laid in wood that is still smoldering. To ensure the survival of the young, the parent beetle secretes a nutritious meal made from microorganisms, fungus, aphids, scale insects and occasionally animal flesh.  Parents groom and guard the offspring to support a healthy brood.

Despite the nasty biting and the damage done by larvae drilling into utility poles, timber structures and fences, fire beetles are actually essential for maintaining the balance of nature. They break down dead and decaying organic matter, recycle nutrients, reduce fuel loads, gobble up aphids and scale insects, and provide delicious larval treats for birds like the black backed woodpecker, another creature who is attracted to burned areas.

In short, Melanophila acuminata are complex, innovative creatures. But we hope they are not causing more trouble (and pain) for our much-appreciated firefighters.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

Photo Credit for Melanophila acuminata by AG Prof. Schmitz

We have endured multiple years of drought, and are probably in store for more. For many of us, it makes sense to replace all or part of our lawn area with less water-intensive plantings.

If you decide to undertake a lawn replacement, make sure you do it properly; incompletely killed grass can regrow amid new plantings, ruining the appearance of your new landscape and creating a maintenance nightmare.  The following three steps will lead to success.

Step One: observe and plan.  What existing trees and plants do you want to keep or remove?  What are the sun and shade patterns within your yard?   What types of grass grow in your lawn?  Do you want any additional amenities, such as paving or a shade structure?  How will you irrigate your new plants? 

Step Two: kill your lawn.  Homeowners can use two eco-friendly methods to kill their lawns: Solarizing or Sheet Mulching. For detailed instructions on solarizing, see UC IPM Pestnote on solarization.  For instructions on sheet mulching, see our Real Dirt blog post on Sheet Composting.

Solarizing uses the sun's radiation to kill lawn grasses as well as many common annual weeds, harmful soil microbes, and seeds down to a depth of 4 to 12 inches in six weeks.  Most beneficial microbes survive, including earthworms.   Solarizing requires six hours per day of full summer sun and takes 4 to 6 weeks to complete.   It works best on fescue, ryegrass, and bluegrass, with partial success on Bermuda grass.  Solarizing must be completed before new plants are installed.

Sheet mulching kills weeds by starving them of light.  It takes 6 to 10 months and can be started any time of the year as long as at least three months of growing season are included.  Sheet mulching works in sun or shade, and is effective on all grasses, including Bermuda grass, and many annual and perennial weeds.  It is left in place permanently; over time, the dead lawn, sheeting, and mulch will break down into soil-enriching compost.  Sheet mulching should be placed before new plants are installed if being used alone to kill lawn or weeds.  It can be placed after plants are installed if solarizing has been completed first.   New hardscape and irrigation should be installed before commencing solarizing or sheet mulching.

A third option for lawn removal is to dig or scrape out the lawn.  Be warned, however, that this method will not kill Bermuda grass and most perennial weeds, which have deep roots that will re-sprout.  If you choose to dig out your Bermuda grass lawn, be sure to follow up with sheet mulching to prevent aggressive regrowth of the grass. 

Step Three: replant.  Whichever method you choose to kill your lawn, time it so that you are ready to replant in the fall, winter, or early spring.  The cool temperatures and moist soils of our wet season allow drought tolerant plants to develop the healthy roots they need to thrive with little water during the heat of summer.  Taking time to thoroughly kill the grass and waiting until the climate conditions are suitable for new plants will ensure the long-term success of a lawn replacement project.

Want more information? Perhaps a hands-on demonstration? A free workshop on How to Remove Your Lawn will be offered on September 26, part of the Master Gardeners' Fall 2024 Workshop Series.  For details, and to register, visit our website.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.