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Top 10 pests in gardens and landscapes and how to control them

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1. Ants

Most people deal with ants around their home at some point. Because most ants live outdoors, focus efforts on keeping ants from entering buildings by caulking entryways. Follow good sanitation practices to make your home less attractive to ants. Spraying ants inside the home will not prevent more ants from entering. Use baits to control the ant colony. Pesticide baits work by attracting worker ants who then take the poison back to the nest where the entire colony, including queens, can be killed. In the landscape, ants protect honeydew-producing pest insects from predators, so use sticky barriers or insecticide baits to keep ants out of trees and shrubs.


2. Aphids

Aphids can curl leaves and produce sticky honeydew, but they rarely kill plants and you usually can wash them off with water. When aphid numbers get high, natural enemies such as lady beetles (lady bugs), lacewings, syrphid fly larvae, soldier beetles and others frequently feed on them, eliminating the need for pesticides. Protect these good bugs by avoiding the use of insecticides that can be toxic to a broad variety of insects. Ants protect aphids from these natural enemies, so keep ants away from your garden as well. When pesticides are necessary, use less toxic products such as insecticidal soaps and oils.


3. Asian citrus psyllid and Huanglongbing disease

The Asian citrus psyllid (ACP) and the deadly bacterial disease it spreads, Huanglongbing (HLB), threaten citrus trees in backyards and on farms. There is no cure or effective control method for HLB disease.  All types of citrus—including oranges, grapefruit, lemons, and mandarins—are affected as well as a few closely related ornamentals. ACP and HLB have already devastated the Florida citrus industry, and now that it is in the Western U.S. it is threatening the California citrus industry as well.


4. Gophers

Gophers are small burrowing rodents that feed on roots of many types of plants. A single gopher can ruin a garden in a short time, and gopher gnawing can damage irrigation lines and sprinkler systems. In lawns, their mounds are unsightly and interfere with mowing. Early detection is critical to prevent damage. Use both traps and underground fencing to manage gopher problems. Toxic baits are available but can pose threats to wildlife, pets, and children, especially in backyard situations.


5. Leaf-feeding caterpillars

Caterpillars, which are the larvae of butterflies and moths, damage plants by chewing on leaves, flowers, shoots, and fruit. Caterpillars in fruit or wood can be difficult to manage because they are hidden most of their life and can cause serious damage even when numbers are low. However, many plants, especially perennials, can tolerate substantial leaf damage, so a few leaf-feeding caterpillars often aren't a concern. Handpicking and beneficial predators and parasites often provide sufficient control. Look for feeding holes, excrement, webbed or rolled leaves, caterpillars, eggs, and good bugs.


6. Peach leaf curl

Peach leaf curl is a fungal disease that affects only peach and nectarine trees. Distorted, reddened foliage in the spring is a distinctive symptom. New leaves and shoots thicken and pucker and later may die and fall off. An infection that continues untreated for several years can lead to a tree's decline. To prevent peach leaf curl, treat peach and nectarine trees with a copper fungicide every year after leaves fall. After symptoms appear in the spring, any treatment will not be effective. When planting new trees, consider buying peach tree varieties that are resistant to the disease.


7. Rats

Rats eat and contaminate food, garden produce, and fruit, and transmit diseases to humans and pets. Manage rats by removing food and shelter, eliminating entryways into buildings, and trapping. Snap traps are the safest, most effective, and most economical way to trap rats. For Norway rats, place traps close to walls, behind objects, in dark corners, and in places where you have found rat droppings. For roof rats, place traps in off-the-ground locations such as ledges, shelves, branches, fences, pipes, or overhead beams. Ensure traps are out of reach of children and pets.


8. Scales

Scale insects suck plant juices and are pests of many trees and shrubs. Infestations can cause yellowing or premature dropping of leaves, sticky honeydew, and blackish sooty mold. Plant parts can distort or die back, depending on the species and abundance of scales. Most plants tolerate low to moderate numbers of scales. Provide plants with proper cultural care, especially irrigation. Encourage scale predators such as lady beetles or lacewings and look for parasite emergence holes in scale covers. Use sticky barriers or insecticide baits to selectively control scale-tending ants. Consider replacing problem-prone plants because most scales are highly specific to certain plants.


9. Snails and slugs

These slimy mollusks emerge from hiding at night and chew holes in leaves and flowers of many succulent garden plants and fruit. Management requires a vigilant and integrated approach that includes eliminating moisture and hiding spots, trapping, setting up barriers, and handpicking. Regularly remove snails from shelters you can't eliminate such as low ledges on fences, undersides of decks, and meter boxes. Place traps in your garden and dispose of trapped snails and slugs daily. Reduce moist surfaces by switching to drip irrigation or watering in the morning rather than later in the day. Consider snail-proof plants such as impatiens, geraniums, begonias, lantana, nasturtiums, and many plants with stiff leaves and highly scented foliage such as sage, rosemary, and lavender.


10. Weeds in landscapes

Prevent weed invasions in new beds with good site preparation. Keep weeds out with an integrated program that includes competitive plants, mulches, and hand removal. Be particularly vigilant about removing aggressive perennial weeds. You rarely should need herbicides in established landscape plantings. Mulches prevent weed seed germination by blocking sunlight. Remove small weeds by hand before they flower and set seed. Use shallow cultivation or hoeing to remove annual weeds from ornamental plantings. Only use herbicides for special-problem situations before establishing new plantings or for difficult-to-control perennial weeds.


To see all of the University of California's Statewide Integrated Pest Management Program's information on home, garden, and landscape pests, visit

For other short pest “Quick Tips” like the ten above, see

 To read even more in-depth, peer-reviewed information on many other common home and landscape pests in California, see the Pest Notes series at

Download your free UC IPM Quick Tips Booklet of the Top Ten Pests in Gardens and Landscapes and How to Control Them with the link below! 

Posted on Friday, June 10, 2016 at 12:30 PM
  • Author: Tyler Ash

Non-native snails introduced by French for escargot

The brown garden snail is found in 26 California counties. It was introduced from Europe 'with an eye to the pot.'
A perennial bane in many California gardens, brown snails were intentionally introduced into a vineyard in the mid-1800s in Santa Clara County "with an eye to the pot," reported Dan Brekke on KQED News. The snails are highly prized in Europe as escargot. The brown snail joined many other species of native and non-native snails and slugs that are detailed on a UC Agriculture and Natural Resources website dedicated to the slimy mollusks.

Approximately 280 species of snails and slugs are found in California; 242 are thought to be native. The vast majority of the native species are not considered to be pests of nurseries or other production systems. 

The most damaging snails and slugs are those that have been accidentally or purposely introduced from areas outside of the US. Most of California's pest gastropods are European species.

Other news:

The Chico News & Review published a profile of local UC ANR Cooperative Extension farm advsior Dani Lightle. Lightle works with Glenn County growers of walnuts, almonds, prunes, olives, pistachios, pecans and fruit. “Basically, if it grows on a tree, it comes my way,” said Lightle, referring to the calls she receives at her Orland office. The article provided background information about UC Cooperative Extension and ANR. "The system's purpose was to be a bridge between public universities and the general public," the article says.

The news website reported on research underway in Northern California on the role of bats in orchard pest control. An intern, under the guidance of UC ANR farm advisor Rachael Long, is comparing orchards with nearby bat boxes with orchards that do not have the convenient dwellings for the flying rodents. "If you increase diversity by relying on insects, bats, raptors, etc., you help strengthen your farming system," Long said.


Posted on Monday, September 28, 2015 at 11:28 AM
Tags: bats (17), Dani Lightle (3), Rachael Long (33), slugs (4), snails (4)

Snails, slugs and spiders star in new UC IPM videos

Brown garden snail
Do you have snails and slugs chewing up your favorite garden plants? Are spiders hanging out in and around your home? How can you get rid of those pesky webs?

The UC Statewide IPM program has just released six short videos to help you find answers to these questions. Find the videos on the UC IPM YouTube channel or linked from the specific Pest Notes publications on Snails and Slugs or Spiders.

Snails and slugs chew holes in leaves and fruit of many different types of plants, but they aren’t always present when the damage is discovered. Caterpillars, earwigs, grasshoppers, weevils, and others cause similar damage. How can you identify the culprit? The short video clip “Did a snail eat my plant?” shows damage caused by various pests and can help you identify snail or slug damage by looking for their characteristic slime trails and excrement.

Snail trap
If you do have snails and slugs in the garden and want to control them without using pesticides, learn how to combine trapping with other nonchemical methods for best results in the clip “Trapping snails and slugs.”  If you decide to use a pesticide, check out the video on ”How to apply snail and slug bait.”  You’ll learn what types of baits are best, which ones to avoid, and how and when to apply them for best results.

Although many people fear them, most spiders you encounter during the day are harmless and can be beneficial in your garden and landscape by eating pest insects. You can see different kinds of spiders in the short clip “Common garden spiders.”

Adult western spotted orbweaver
However beneficial they may be, you might not want them inside your home. Even though the easiest method of getting rid of a spider is to kill it, why not trap it and let it loose outdoors to eat those garden pests? “How to catch a spider” shows several ways to easily trap a spider and let it go, including two types of nifty spider catchers that catch spiders in hard-to-reach places. Now what about those sticky webs?  “How to clean up spider webs” shows practical methods for removing webs from around your home such as vacuuming, sealing holes in cracks or screens, hosing them off, or using a Webster tool.  These methods can also help to keep spiders out of your home. 

For more information on snails, slugs, spiders, and other home and garden pests, visit the UC IPM web site.


Posted on Friday, August 9, 2013 at 2:13 PM
  • Author: Cheryl Reynolds, UC Statewide IPM Program
Tags: IPM (40), slugs (4), Snails (4), spiders (35)

A Sheltered Life

Initially the strawberries started off planted around my grape vine planted in a a half wine barrel. But as strawberries do, they formed runners and clambered out of the barrel. Over the years they had formed a little area at the foot of the barrel, just off the corner of the patio.  Unfortunately at the same time, the vinca minor had spread from its intended area.  At first I thought everything would be okay, the strawberry plants were sort of growing on top of the vinca and it looked kind of cute. Over the years, I found myself getting fewer and fewer strawberries. By the time they would ripen they would have been reduced to pathetic shells by slugs and snails.  I don't like to use snail pellets so I was continually on the lookout  for snails and slugs each morning when I watered my plants.

I finally realized that the vinca was creating the perfect environment for the slug/snail contingent. During the day they would rest in the cool, dark, moist area provided under the vinca strands.  At night they would crawl up and feast on the strawberries. So early this spring, I decided that the vinca under the strawberries had to go.  If you've never pulled up vinca, it's a little like pulling bindweed. I also had to be careful that I didn't pull up the strawberry plants at the same time.  It took quite a bit of time and effort, but finally it was done.

I have really been impressed with the change. I am actually getting strawberries again and losing far fewer to slug predation. Now I just have to keep my eye on the birds.

Escaped strawberries. (photos by Karen Metz)
Escaped strawberries. (photos by Karen Metz)


Posted on Wednesday, May 8, 2013 at 8:22 AM
Tags: barrel (1), control (3), environment (11), slugs (4), snails (4), strawberries (27), Vinca minor (1)

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