[From the UC IPM blog Pests in the Urban Landscape]

We all encounter pests in our homes, gardens, and landscapes, but which ones are most popular in California? While we can't say for certain, website traffic to UC IPM's Pest Notes gives us a glimpse of popular pests. Here are the top ten most frequently viewed publications in 2021.

1. Aphids

These insects may be small, but they can quickly build up large populations. With many different species in California that feed on vegetables, flowers, fruit trees, and woody ornamentals, aphids are a common sight in landscapes and gardens. Year after year, aphids continue to hold the top spot. Learn more about aphids and their management in Pest Notes: Aphids. 

2. Fungus Gnats

This pest has become more popular in recent years, perhaps a result from growing numbers of houseplant enthusiasts. Fungus gnats are small flies that often infest soil and potting mix. They can be a common houseplant problem with larvae, or immatures, damaging roots and stunting plant growth when present in large numbers. More information on these frustrating flies can be found in our Pest Notes: Fungus Gnats.

3. Thrips

Another tiny insect sometimes found on houseplants, thrips are slender insects about the size and shape of a dash printed in a newspaper. They suck out the cell contents, leaving a discolored speckling on leaves or stunting plant growth. For more about thrips monitoring and management, visit our Pest Notes: Thrips.

4. Mealybugs

If you've found soft, oval insects that are white in color with wax filaments on your indoor or outdoor plants, it is likely you have mealybugs. These wingless insects are often found in clustered colonies. In yards and gardens, handpicking, pruning, or high-pressure water sprays can reduce populations. For small infestations indoors, spot treatments may help reduce populations. For houseplants with severe infestations, consider disposing of the plant. Find additional information in Pest Notes: Mealybugs. 

5. Carpet Beetles

Immature carpet beetles feed on natural fibers such as wool, silk, or furs. The adults may be brought into the home on cut flowers or when they fly in through open doors, windows, or holes in screens. Regular cleaning of rugs, upholstered furniture and can prevent infestations or reduce damage. Check out the Pest Notes: Carpet Beetles for more information.

6. Peach Leaf Curl

Peach leaf curl can affect the blossoms, fruit, leaves, and shoots of peach and nectarine trees. The symptoms of the disease first appear in spring, when distorted red foliage emerges. However, focus management for nonresistant varieties in the late fall and early winter, after leaves drop. Read more about this disease in our Pest Notes: Peach Leaf Curl.

7. Clothes Moths

New to the top ten list this year were clothes moths. These pests tend to hide when disturbed, so you may not realize you have an infestation until after the moths have already damaged fabric, fur, or feathered items. Some clothes moths make webs while others are casemaking moths. Regularly monitoring and cleaning clothing and storage areas can help prevent or reduce infestations. Find more identification and management information from Pest Notes: Clothes Moths.

8. Springtails

Springtails made an unexpected appearance on this year's top ten list. These are small, jumping insects that can be found near kitchen sicks and bathtubs as well as in the soil of indoor houseplants. They often appear in the spring and early summer but can be found year-round in moist environments. They get their name because they jump when disturbed. Learn more about this pest in Pest Notes: Springtails. 

9. Whiteflies

Whiteflies are not actual flies but are tiny insects that are often found on the underside of leaves, feeding on the phloem of many different plants. Certain species can cause significant loss in vegetable gardens; other species found in fruit trees are less damaging. Both adult and immature whiteflies also attack houseplants.  Management information can be found in Pest Notes: Whiteflies.

10. Scales

Scales are small, legless insects that look like tiny scabs on the stems, leaves, or fruit of plants. While some scale species can weaken a plant when abundant, other species do not appear to damage plants at all. Think you have a problem with these insects? Visit our Pest Notes: Scales for identification and management options.

We all encounter pests in our homes, gardens, and landscapes, but which ones are most popular in California? While we can't say for certain, website traffic to UC IPM's Pest Notes gives us a glimpse of popular pests. Here are the top ten most frequently viewed publications in 2021.

1. Aphids

These insects may be small, but they can quickly build up large populations. With many different species in California that feed on vegetables, flowers, fruit trees, and woody ornamentals, aphids are a common sight in landscapes and gardens. Year after year, aphids continue to hold the top spot. Learn more about aphids and their management in Pest Notes: Aphids. 

2. Fungus Gnats

This pest has become more popular in recent years, perhaps a result from growing numbers of houseplant enthusiasts. Fungus gnats are small flies that often infest soil and potting mix. They can be a common houseplant problem with larvae, or immatures, damaging roots and stunting plant growth when present in large numbers. More information on these frustrating flies can be found in our Pest Notes: Fungus Gnats.

3. Thrips

Another tiny insect sometimes found on houseplants, thrips are slender insects about the size and shape of a dash printed in a newspaper. They suck out the cell contents, leaving a discolored speckling on leaves or stunting plant growth. For more about thrips monitoring and management, visit our Pest Notes: Thrips.

4. Mealybugs

If you've found soft, oval insects that are white in color with wax filaments on your indoor or outdoor plants, it is likely you have mealybugs. These wingless insects are often found in clustered colonies. In yards and gardens, handpicking, pruning, or high-pressure water sprays can reduce populations. For small infestations indoors, spot treatments may help reduce populations. For houseplants with severe infestations, consider disposing of the plant. Find additional information in Pest Notes: Mealybugs. 

5. Carpet Beetles

Immature carpet beetles feed on natural fibers such as wool, silk, or furs. The adults may be brought into the home on cut flowers or when they fly in through open doors, windows, or holes in screens. Regular cleaning of rugs, upholstered furniture and can prevent infestations or reduce damage. Check out the Pest Notes: Carpet Beetles for more information.

6. Peach Leaf Curl

Peach leaf curl can affect the blossoms, fruit, leaves, and shoots of peach and nectarine trees. The symptoms of the disease first appear in spring, when distorted red foliage emerges. However, focus management for nonresistant varieties in the late fall and early winter, after leaves drop. Read more about this disease in our Pest Notes: Peach Leaf Curl.

7. Clothes Moths

New to the top ten list this year were clothes moths. These pests tend to hide when disturbed, so you may not realize you have an infestation until after the moths have already damaged fabric, fur, or feathered items. Some clothes moths make webs while others are casemaking moths. Regularly monitoring and cleaning clothing and storage areas can help prevent or reduce infestations. Find more identification and management information from Pest Notes: Clothes Moths.

8. Springtails

Springtails made an unexpected appearance on this year's top ten list. These are small, jumping insects that can be found near kitchen sicks and bathtubs as well as in the soil of indoor houseplants. They often appear in the spring and early summer but can be found year-round in moist environments. They get their name because they jump when disturbed. Learn more about this pest in Pest Notes: Springtails. 

9. Whiteflies

Whiteflies are not actual flies but are tiny insects that are often found on the underside of leaves, feeding on the phloem of many different plants. Certain species can cause significant loss in vegetable gardens; other species found in fruit trees are less damaging. Both adult and immature whiteflies also attack houseplants.  Management information can be found in Pest Notes: Whiteflies.

10. Scales

Scales are small, legless insects that look like tiny scabs on the stems, leaves, or fruit of plants. While some scale species can weaken a plant when abundant, other species do not appear to damage plants at all. Think you have a problem with these insects? Visit our Pest Notes: Scales for identification and management options.

 

We took a look at which titles were of greatest interest during the first five months of the COVID-19 pandemic when many Californians were staying home. These are the top ten most viewed Pest Notes from March to August 2020.

#10 Pocket Gophers

Pocket gophers are active all year round but, in the springtime, young gophers are on the move so people might see more damage then. A single gopher can quickly ruin a garden but you probably won't see it. You'll need to watch out for their mounds to clue you in.

Got gophers? You can control these pesky rodents with traps. See our videos for instructions on how to find gopher tunnels, where to place gopher traps, and how to set Macabee and Gophinator traps.

Get more details at Pest Notes: Pocket Gophers.

#9 Whiteflies

Whiteflies are tiny, sap-sucking insects that can become abundant in vegetable and ornamental plantings, especially during warm weather.

Signs of a whitefly infestation can include:

• Tiny nymphs on the underside of leaves.
• Sticky honeydew on leaves, fruit, or beneath plants, or a covering of black sooty mold.
• Yellowing, silvering, or drying leaves that have whitefly nymphs on them.
• Deposits of white wax (with certain whiteflies).

For more information and management tips, see Pest Notes: Whiteflies.

#8 Scales

Scales are immobile insects that suck plant juices from many types of trees, shrubs, and houseplants.

What does scale damage look like?

Damage resembles that of aphids and whiteflies. There is abundant sticky honeydew (excreted by soft scales and certain other species). Black sooty mold may be growing on the honeydew. Discolored, distorted, or dying leaves, twigs, or branches (especially with armored scales) may be present.

Need to know more? See Pest Notes: Scales.

#7 Carpet Beetles

Carpet beetles can be found in homes, warehouses, museums, or anywhere else fabric, furs, and feathers are present.

How did carpet beetles get in my house?

• Carpet beetle adults are pollen feeders and are found on flowers with abundant pollen like crape myrtle, spiraea, and buckwheat.
• People often bring carpet beetles into their homes on cut flowers from the garden.
• Adults can fly in through open windows or doors without screens.

If you think you've got carpet beetles and need to know how to get rid of them safely and effectively, read Pest Notes: Carpet Beetles.

#6 Ground Squirrels

Ground squirrels may be cute and furry but they can injure many types of plants, harbor diseases harmful to humans, and damage landscapes with their burrowing.

Ground squirrels cause damage by, eating food-bearing and ornamental plants, gnawing on plastic sprinklers and irrigation lines, girdling young trees, and burrowing, which causes trip hazards and damages landscapes and structures.

Learn more at Pest Notes: Ground Squirrel.

#5 Thrips

Thrips are tiny, slender insects but you're more likely to see the damage they cause than the insects themselves. When thrips feed, they distort or scar leaves, flowers, or fruit. 

You often won't see damage  until tissue grows and expands. Look for:

• Scabby, silvery to dark brown discoloration on fruit, leaves, or petals
• Dark specks of excrement on fruit or leaves
• Distorted, curled, galled, or dead shoot tips and leaves

Thrips are difficult to control. You'll need to combine methods for best results. For more information, see Pest Notes: Thrips.

#4 Mealybugs

Mealybugs are small, soft, wax-covered insects that are common problems on houseplants and on outdoor plants in areas with mild winters.

What do mealybugs look like?

Most adult mealybugs are wingless females with oval, segmented bodies covered with wax. Males have wings but are rarely seen. Newly hatched mealybug immatures move around plants but soon settle down and produce a waxy covering. Different mealybug species can be distinguished by the length of the waxy filaments around their bodies. They may be confused with other insects that produce wax and honeydew like cottony cushion scale, woolly aphids, soft scales, and whiteflies. Mealybugs are sometimes hard to see. They often live in protected areas of plants such as in the crown of a plant, in branch crotches, or on stems near the soil.

Mealybugs suck sap, weakening plants. High populations can slow plant growth and cause leaf drop. For help managing mealybugs, read Pest Notes: Mealybugs.

#3 Aphids

Almost every plant has one or more aphid species that occasionally feed on it, so it's no wonder that so many people viewed this publication. Although aphids can curl leaves and produce sticky honeydew, they rarely kill plants, and can usually be washed off with water.

How can you reduce aphids?

• Prune infested leaves and stems.
• Knock aphid populations off plants by shaking the plant or spraying it with a strong stream of water.
• Protect seedlings with covers or aluminum foil mulches.
• Wait for hot weather; some aphids are heat-intolerant and will be gone by mid-summer.

Still have questions? Find out more about aphids in Pest Notes: Aphids.

#2 Fungus Gnats

Fungus gnats are small flies that infest soil, potting mix, other container media, and other sources of organic decomposition. Because adult fungus gnats are attracted to light, you first might notice these pests flying near windows indoors. If you spot fungus gnats flying around, check your plant pots. If the soil in the pots is overly moist, fungus gnat larvae could be feeding on the plant roots.

What can you do about fungus gnats?

Avoid overwatering and provide good drainage. Allow the surface of container soil to dry between waterings. Clean up standing water, and  eliminate any plumbing or irrigation system leaks. Avoid using incompletely-composted organic  matter in potting media unless it is pasteurized first, because it will  often be infested with fungus gnats. Screen and caulk leaky windows and doors to help prevent pests like fungus gnats from coming indoors.

For more management tips, read Pest Notes: Fungus Gnats.

#1 Peach Leaf Curl

Our top viewed Pest Notes was peach leaf curl, a fungal disease that affects only peach and nectarine trees. Distorted, reddened foliage in spring is a distinctive symptom of peach leaf curl. Unfortunately by the time you see symptoms, it's too late to do anything this year. In order to manage this disease, treat trees with a fungicide in late fall and winter.

How do you effectively manage peach leaf curl?

• The fungal spores that cause the disease spend the winter on twigs and buds and germinate in the spring.
• For effective control, treat trees just after leaves have fallen, usually late November or December.
• Consider a second application in late winter before buds swell, especially in areas with high rainfall or during wet winters.
• Don't apply fungicides during the growing season because they won't be effective.

For more information see Pest Notes: Peach Leaf Curl.

 

It's been a buggy spring and summer in my new garden, where I've encountered varieties of scale, aphids and flies I hadn't experienced before. About 18 months ago we moved to a new house in a new neighborhood.  With some exceptions, the general goal for our new, smaller garden was to plant drought-tolerant, pollinator-friendly plants, use California natives whenever possible, and encourage beneficial insects.    

Aphids

This spring I planted milkweed seeds obtained from the La Loma Native Garden in Modesto. In May, I discovered the now 6-inch-tall plants were covered from top to bottom with orange-yellow aphids! I learned they are called oleander aphids which are a common pest of milkweed. The leaves of the milkweed looked as if they had white spots all over them.

According to UC Integrated Pest Management (UC IPM), aphids are small, soft pear-shaped bodied insects with long legs and antennae, with slender mouthparts used to pierce stems, leaves and other tender plant parts to suck out plant fluids. The site recommends first attempting to control aphids by washing them off with a gentle stream of water. I did this over several mornings and evenings, with my hose set on fine spray, washing both the top and underside of the leaves. After about a week, I still had quite a few aphids, so I sprayed an insecticidal soap, making sure I covered both the top and bottom of leaves. Aphids produce many offspring, so they required an additional treatment. 

Scale Insects

I brought with me from the old house three pots of cyclamen plants given to me by former students.  These plants were the source of my first insect attack during the spring, which was soft scale.  I've had these plants for 15-20 years have never had a bug problem.  One pot was particularly hard hit with leaf tips appearing browned and wilted, often dropping off.  A sticky honeydew also appeared. Unlike hard scale, which I've experienced with olive trees, where the insect is underneath an armored cover and do not produce honeydew, the soft scale surface is the actual body wall of the insect and cannot be removed.  

Soft scale is a sucking insect, appearing as tiny dots on the leaves or stems of a plant. They can grow up to ¼ inch long and have a smooth, cottony or waxy surface. They feed on the sap of the plant and excrete sticky honeydew, which can attract ants.  Mine were brownish-yellow with a waxy color, usually appearing on the underside of the leaves. 

I removed badly damaged leaves, checked undersides of the leaves for the scale and scraped off any scale I found using a wet Q-tip.  I also checked my other two plants and occasionally found a scale or two on them, scraping them off also.  I repotted the infested plant with potting mix. Over time I was able to completely get rid of the soft scale.

Whiteflies

My final insect encounter was with whiteflies. I've been planting bulbs the past few years, planting dahlias for the first time this spring, which started to bloom in June. The whiteflies showed up in July, particularly infesting the two large white dinner-plate dahlias. The leaves on the plant became mottled yellow. Another sap-sucking insect, whiteflies are not true flies, but are related to aphids, scales, and mealybugs. Adults are tiny insects with a white wax covering on their wings and body. I spent a week trying to wash the whiteflies off with a heavy mist spray of water both on the top and bottom of leaves twice a day, but, it didn't manage them well enough. I switched to spraying on a weekly basis with an insecticidal soap, thoroughly covering both the top and bottoms of the leaves, which has reduced the infestation to a manageable level. Since these dahlias are annuals, not being able to completely eliminate the whiteflies is acceptable in my view. 

 My Buggy Summer Summary

It has been an educational summer learning about these insect pests and dealing with their infestations. I'm gratified I've been able to manage them using less toxic pesticides that are less harmful to beneficial insects and the environment. You can learn more about less toxic pesticides such as insecticidal soaps and oils by visiting the UC IPM website or by watching this video. 

Denise is a UCCE Stanislaus County Master Gardener.