Ask the Experts

University of California Cooperative Extension (UCCE) Master Gardeners of San Mateo/San Francisco Counties is now one of our expert sources helping to provide responses to pest inquiries submitted by our website visitors.

Email us at experts@hungrypests.com with a question. Be sure to include the name of your city or county in your email.

I’m a gardener and have a large healthy Meyer lemon tree that produces a great deal of fruit, more than I can possibly use myself. I have relatives in colder parts of the country that often ask me to send them some lemons. I haven’t done so, because I don’t want to spread the LBAM, but they all think I’m being irrationally fearful, since they plan to consume the entire lemon. Most of the official guidelines seem to be aimed at farmers or commercial enterprises and not at backyard gardeners. Is there some way to treat small amounts of picked fruit (bleach bath, brief microwaving, etc.) so it wouldn’t be a risk? Is there a way to tell if a citrus fruit has been compromised by moth larvae, the way you can see codling moth holes on an apple?

Because there are no single tools or methods that can be relied upon to quickly eliminate LBAM from all infested areas, control programs integrate a number of strategies. One of the key strategies is limiting and containing the LBAM population to its present distribution (quarantines). So while it’s tempting to share the bounty your lemon tree provides, the risk of spreading LBAM out of the quarantine area is too high. Per a recent conference call, we have received information that homegrown fruits and vegetables (including leafy green vegetables), though not cut flowers or decorative greens, may be transported within the confines of a quarantined area, including donations to food banks. Any fruit or vegetables that are spoiled or damaged should not be transported in any manner. For further information contact the California Department of Agriculture, San Mateo County Health System – Agriculture or the San Mateo County Agriculture Commissioner’s Office, 728 Heller St., Redwood City, CA 94064 Phone: (650) 363-4700 Fax: (650) 367-0130.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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There is some pest eating away my young magnolia leaves, they seem
to attack the baby leaves which haven’t even unfolded yet. It would be great if you could help me identify the culprit.

  1. Type and age of plant: Magnolia – 1 year old, 6 feet tall
  2. Specific problem/question: Pest eating young leaves
  3. History/details of problem/question: Usually  happens in early spring when young leaves are shooting out
  4. Recent watering, fertilization, insecticide applications: Some oil application<
  5. Photos: http://picasaweb.google.com/jameshtsun/Magnolia#

–Noe Valley neighborhood of San Francisco

Sometimes when magnolias come into leaf the leaves will suddenly vanish or turn brown or turn into leaf skeletons. This is the work of small slugs which emerge in damp weather, usually overnight, to take their fill of young magnolia shoots and leaves. Snails may also be responsible, but you seldom actually see them at work.

In late winter/early spring as the leaves unfurl, you should take measures to prevent a snail and slug attack (see suggestions in the UC IPM pest notes, http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7427.html). Possibly add a slug bait (something with Iron Phosphate as it is non-toxic to pets and wildlife) to the base of the plant and repeat this after rain for a couple of weeks until the leaves are fully formed. After two or three years of growth the plants can usually withstand a slug attack but not before their root systems have formed properly.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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Your [HungryPests] website is very interesting and informative and I’ll keep an eye out for these pests for sure, I know I’ve seen the apple moth in my yard in Hollister.

I’ve also seen a great number of some other pests that I cannot identify. I was hoping you could help or direct me to someone who can. We have always struggled with white flies, but last year we began to see something that looks like a black version of these. We had so many on our cherry tree last year that it looked as though it had gone moldy and the fruit was completely un-edible. When I was weeding and mowing my front yard and nearly everywhere a small swarm of these came up from the plants and landed back down (much as white flies will do).

I try not to overspray my yard on behalf of the environment and my two curious cats, but I have worked really hard at developing a nice looking, healthy and in the case of our four fruit trees (peach, cherry, apricot, and apple) productive yard. I don’t want to lose everything to these very invasive and hungry pests.

It is difficult to tell from your brief description what the insect is on your cherry tree. In order for us to be more helpful we need additional information. What time of year did you first notice the pest? Do you see any damage to the leaves, stems, or just on the fruit (i.e. chewed leaves, sunken areas on the fruit that become moldy etc.)? Do the black insects all fly or just some of them? How big is the insect? Does the black fly occur on other plants? If so, what kind? A high quality digital picture could be very helpful. If you answer some of these questions we can be more definite in our identification of your pest. You can email us mgvhelpline@ucdavis.edu.

In the meantime, here is a link for more information about Cherry pest management and helpful information for taking care of fruit trees: http://www.ipm.ucdavis.edu/PMG/selectnewpest.cherries.html.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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I have an Asian Apple tree and a Pear tree and every year I end up with holes in my fruit. After checking on Internet, it seems like this might be caused by Apple Maggot flies. I just wanted to confirm with you that this is the correct bug causing the problem in the Modesto, CA area?

Also what are the ways to fight this? Is Kaolin Clay or sticky red balls hanging from the trees effective for a couple of back yard trees? I really do not want to spray with things such as Sevin as I am afraid it is not the best and organic way to go.

– Modesto, CA

From your description it sounds like you have a problem with Codling moth.  This can be a problem on Asian apple and pear trees. The Codling moth has a 0.5 to 0.75 inch wingspan. The tip of each forewing has a coppery-tinged, dark brown band that distinguishes codling moth from other moths found in apple orchards. Females lay eggs singly on leaves and sometimes on fruit later in the season. The eggs are smaller than a pinhead, disk-shaped, and opaque white when first laid. Just before hatching the black head of the larvae becomes visible. Newly hatched larvae are white with black heads. Mature larvae are 0.5 to 0.75 inch long, pinkish white, with mottled brown heads. Depending on climate conditions and location in the state, there are two to four generations of codling moth each year.
Codling moth has the greatest potential for damage of any apple pest, yet it can be effectively controlled with properly timed treatments. It causes two types of fruit damage: stings and deep entries. Stings are entries where larvae bore into the flesh a short distance before dying. Deep entries occur when larvae penetrate the fruit skin, bore to the core and feed in the seed cavity. Larvae may enter through the sides, stem end or calyx end of the fruit. One or more holes plugged with frass on the fruit’s surface are a characteristic sign of codling moth infestation.

There are a couple of effective ways to manage codling moths that are consistent with organic farming principles. Organically acceptable tools include cultural control in conjunction with mating disruption and sprays of approved oils, codling moth granulovirus (Cyd-X), the Entrust formulations of spinosad and kaolin clay (Surround).

Please check out the links below for characteristic damage description and the best way to effectively address pest management including organically sustainable methods:

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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I have a small urban garden. Something is eating tender foliage in my garden – it attacked new gardenias (and ate all foliage), hydrangeas, as well as four basil plants (planted in succession).  I am now finding that my mint plants are being eaten.

Someone told me it was caterpillars (although I did not see any telltale droppings), so I sprayed with special caterpillar spray. It halted the damage to the gardenias and they started to grow new leaves, but are now being nibbled again.

I have also tried snail/slug bait and spraying with a general (supposedly safe) insecticide.  But the basil and mint are being chewed to the stems. The Hydrangeas just look moth-eaten and the oregano is dotted with holes.

– San Francisco, CA

If your plants are being chewed and eaten right now, a likely culprit would be caterpillars. Look carefully at the undersides of your plants. Caterpillars are the larval stage of moths or butterflies and are often various shades of green that blend in well with the foliage they are eating. Many caterpillars chew holes in the leaves. Young caterpillars can produce ‘windows’ in the leaf, where only the underside is removed, leaving the upper surface intact.  Caterpillar damage can usually be distinguished from slug or snail damage by the presence of caterpillar droppings (‘frass’, often barrel-shaped) on the leaves and the lack of slime trails.

Because your leaf eater subject referred to edible plants, we recommend continuing a safe IPM solution as described by this UC Davis IMP website:


You can also try using soap sprays as insecticides. There are a few different methods to try.

Two kinds of soaps are available for home use: commercial solutions such as Safer’s Insecticidal Soap®, and those made at home with household products. To use an insecticidal soap, mix the concentrate with water as directed on the label. Safer’s is registered for use on both ornamentals and edible crops. Wayne S. Moore and his Cooperative Extension colleagues at the University of California, Berkeley, reported that optimum control with minimum risk to plants could be achieved with a one- or two-percent solution of liquid dishwashing detergent, or about one to two tablespoons of detergent to a galIon of water (Cakufirbua Agriculture, June 1979). Solutions made with powdered or liquid laundry detergents and powdered dishwashing detergents were found to be too harsh to plants and are not recommended. You should be aware, however, that the effectiveness of sprays made from household products may be quite variable.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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How do you get rid of carpet beetles?

For comprehensive information on a carpet beetle problem, please check out the link and read this article: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7436.html. Carpet beetles are among the most difficult indoor pests to control because of their ability to find food in obscure places and to disperse widely throughout a building. Successful control depends on integrating the use of sanitation and exclusion and, where necessary, insecticides.

Sticky traps are available with or without a pheromone; these traps can be placed on window sills to trap adults that fly to windows. Traps placed throughout a building can show where beetles are coming from; the traps are also useful for monitoring the effectiveness of control applications. Check traps once or twice a week. Plain sticky traps are available in retail stores; sticky traps with a pheromone can often be purchased from local pest control operators or from distributors of pesticide supplies.

Eliminate the Source

Eliminate accumulations of lint, hair, dead insects and other debris that serve as food for carpet beetles. Throw out badly infested items. Remove bird, rodent, bee and wasp nests, and old spider webs, which may harbor infestations. Examine cut flowers for adult beetles. Regular and thorough cleaning of rugs, draperies, upholstered furniture, closets and other locations where carpet beetles congregate is an important preventive and control technique. Frequent, thorough vacuuming is an effective way of removing food sources as well as carpet beetle eggs, larvae and adults. After vacuuming infested areas, dispose of the bag promptly because it may contain eggs, larvae or adult insects.

Protect fabrics by keeping them clean: food and perspiration stains on fabrics attract carpet beetles. Dry cleaning or thoroughly laundering items in hot water kills all stages of these insects. This is the most common method used to control fabric pests in clothing, blankets, and other washable articles.

Some furniture, mattresses and pillows are stuffed with hair or feathers. When carpet beetles or clothes moths get into the stuffing, they cannot be controlled simply by spraying the outside surface of the item. The best way to eliminate them is to have the infested item treated with lethal gas in a fumigation vault. This service is provided by some pest control and storage firms. Because of the potential hazards to the applicator of the fumigant, only licensed pest control operators can buy and use them. However, proper fumigation gives quick, satisfactory control, and kills all stages of fabric pests. It does not prevent re-infestation.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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I have a question about my pear tree in my backyard. I would like to know how I can take care of the fruit because all of the fruit have black dots. Can you tell me what to do? By next year will it be okay?

It sounds like you are dealing with Pear Scab, which is a fungus. Scab first appears as velvety, dark olive-to-black spots on fruit, leaves, and stems. When infections occur early, fruit spots become scab-like with age and the fruit may become misshapen. On leaves, infections cause leaf puckering and twisting and eventually tear with age. Secondary infections that occur later in the season appear as black, velvety pinpoint spots on fruit and leaves.

In California, the fungus overwinters in dead leaves on the ground. Primary spores are discharged from infected dead leaves during spring rains and infect young leaves and fruit during periods of prolonged moisture. These infections produce secondary spores, which may cause further spread of disease during wet periods. Pear scab outbreaks can be predicted based on temperature and moisture conditions. The main objective in scab management is the reduction or prevention of primary infections in spring. Extensive primary infections result in poor fruit set and make scab control during the season more difficult. If primary infections are successfully controlled, secondary infections will not be serious.

Pear scab is best treated by using dormant sprays during the winter. For comprehensive information on Pear Scab please read the UC IPM article:


– UCCE Master Gardeners of San Mateo/San Francisco Counties

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My pantry was infested with Grain Weevils (those black pointed nose pests). I had to throw out a lot of my grains and food, but I am still finding a few of them around the house. Do I have to bug bomb my house or do you know of a non-toxic remedy?

Getting rid of food-infesting moths or beetles takes continuous, persistent effort if the infestation has been present for a while. Some pests are capable of living for many weeks without food, thus the threat of re-infestation exists until they die off or are killed. Follow the guidelines for removing and cleaning up an infestation. It is best, at least for several months after eliminating the infested products, to store any susceptible food in airtight containers or in a refrigerator or freezer. Also, as a general practice, storing infrequently used food items (e.g., pancake flour, grains, spices, etc.) in the freezer prevents infestations from developing.

Most home infestations of pantry pests maintain themselves on spills in the crevices of cupboards and drawers or in opened packages of food stored for long periods of time. Following a few general guidelines when storing food products will help you avoid many potential problems:

  • Do not put exposed food on shelves. Place it in containers with tight-fitting lids (plastic bags are not adequate).
  • Regularly clean shelves, bins, and all other locations where there is any possibility of flour or other food particles accumulating. Certain pests need only small amounts of food to live and breed. Soap and water is great for cleaning flat areas, and vacuuming with a crevice attachment will help clean cracks, edges, and corners.
  • Do not mix old and new lots of foodstuffs. If the old material is infested, the pest will quickly invade the new.
  • Clean old containers before filling them with fresh food. They may be contaminated and cause a new infestation.
  • Do not purchase broken or damaged packages of food materials. They are more likely to become infested.
  • Construct storage units so that they are tight and can be cleaned easily.
  • Store bulk materials, such as pet foods, in containers with tight-fitting lids.
  • Keep storage units dry. This is important because moisture favors the development of pantry pests; dryness discourages them.
  • Some pantry insects breed in the nests of rodents and insects and may migrate from these into homes. Eliminate any nests found in or near the home.
  • Pantry pests can also breed in rodent baits. Be sure to frequently check and discard infested baits.

For more information read the UC IPM article: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7452.html.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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Our bell pepper and tomato plants have been devoured by large green caterpillars. The plants look to be clear of them at night, but the next day the plants have been eaten down to the stalk, and we are pulling off, and killing the caterpillars! They are probably 4 to 5 inches long. Can you tell us what they are, and how we can get rid of, or prevent them?

It sounds like you are dealing with Hornworms. These caterpillars are so big (three inches long or more) that it would seem to be easy to control them just by picking them off. And so it is, sometimes. The problem is that their pale green color provides excellent camouflage, and the nymph and larval stages are far smaller and less obvious. If there are only a few, picking them off works well. One site suggests spraying the plant with water, causing the caterpillars to, and I quote, “thrash around,” giving themselves away. If there are more than a few, other measures may be called for.

One of these is Bt, Bacillus thuringiensis, an organic treatment that can control numerous other problems as well. There are other options to try for controlling Hornworms and there are several important naturally occurring parasites that help control hornworms in tomatoes. Hornworm eggs are attacked by Trichogramma parasitesz and the larvae by Hyposoter exiguae. Trichogramma released for control of tomato fruitworm will also attack hornworm eggs. Discing after harvest destroys pupae in the soil. Rotations with crops that are not attacked by hornworms will also help to keep population levels low in individual fields. These biological and cultural controls as well as Bacillus thuringiensis sprays are acceptable for use on an organically certified crop. For more information, read the pest management guidelines: http://www.ipm.ucdavis.edu/PMG/r783301111.html.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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I may have found Mediterranean fruit fly egg cases on my property. Unfortunately I was unable to identify them before they hatched. What should I do?

[Please include information about what to do in the future if invasive pests are suspected.]

Contact the San Mateo County Department of Agriculture Vector Control District at (650) 344-8592. A Biologist is available Monday through Friday in the afternoon at the main office (728 Heller Street, Redwood City) to assist homeowners and pest control businesses with the identification of landscape, home and structural insect pests, weeds and plant diseases. Effective control methods are recommended with an emphasis on integrated pest management.

You can also visit http://www.co.sanmateo.ca.us/ for more contact details.

– UCCE Master Gardeners of San Mateo/San Francisco Counties

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