- Author: Lauren Fordyce
While preparing your garden for planting this spring, you may have found white grubs in the soil. Discovering these fairly large, white grubs can be alarming, but they usually won't cause significant plant damage.
Grubs are the soil-dwelling larvae of beetles in the Scarabaeidae family, also simply called scarabs. They are generally curled in a C-shape with whitish bodies and 6 legs. Grubs of some species may be less than 0.5 inch long, while other species may be up to 2 inches. Some grubs feed on living plant material while others do not.
Masked chafer beetle grubs are often what people find in garden beds in California. If you find large grubs in compost, those are likely the larvae of the green fruit beetle (also commonly called figeater beetle and green fig beetle). Japanese beetles are not usually present in California, but there are a few small hot spots under eradication efforts by the California Department of Food and Agriculture.
In most cases, the presence of grubs does not require pesticide treatment and populations of 6 or less per square foot won't cause significant damage. If you notice them in your garden beds, they can be hand-picked and killed. Some may choose to feed them to their backyard chickens or leave them out for wild birds. Beneficial nematodes can be applied to control grub infestations.
To learn more about common white grubs, visit https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=56797
Spring is here and if you are like us, you can't wait to get outside and see how your plants and garden are doing! As usual, UC IPM has useful tips for the month of April to prevent pests in the garden and landscape. To see more tips specific to your region, visit the Seasonal Landscape IPM Checklist on the UC IPM website. Here are some general tips to get you started:
- Cover fruit trees with netting to exclude birds and other vertebrate pests.
- Aphids are out already so look for them and their natural enemies such as predaceous bugs like lacewings, lady beetles, and syrphid flies. On sturdy plants, spray aphids off with a strong stream of water or apply insecticidal oils or insecticidal soaps to kill them.
- Manage ants. Plants infested with honeydew producing insects like aphids, whiteflies, and mealybugs may attract ants who take that honeydew back to the nest to feed the colony. Manage ants around landscape and building foundations using insecticide baits and trunk barriers.
- Whitewash tree trunks to deter borers and prevent sunburn. Apply to young trees or older bark on susceptible trees newly exposed to sunlight.
- Look for signs of clearwing moths boring in ash, birch, pine, poplar, and willow.
- Check for signs of powdery mildew on apple, crape myrtle, grape, rose, and stone fruits. Take preventative measures, like pruning, to provide better air circulation between plants.
- Watch for yellowjackets and other wasps building nests in undesirable locations. Knock down newly started nests and use lure or water traps to control populations.
- Prevent mosquitoes by eliminating standing water in gutters, drain pipes, flowerpots, etc. Place Bt “dunks” (Bacillus thuringiensis subspecies israelensis) in birdbaths and ponds to selectively kill mosquito larvae.
- Adjust watering practices as rainfall decreases. Check irrigation systems for leaks and broken emitters and perform maintenance as needed. Consider upgrading the irrigation system to improve its water efficiency.
- Monitor stone fruit trees for pests such as aphids, borers, brown rot, caterpillars, powdery mildew, and scale insects.
Don't see your county on the checklist or want to provide feedback? Let us know!
Below are answers to UC IPM's 2024 insect Easter egg hunt! Click on the name of each insect to learn more.
These eggs belong to the brown marmorated stink bug (BMSB) a pest of many types of plants and occasional indoor nuisance. BMSB females will lay up to 28 white or pale green eggs in a cluster. There are over 50 stink bug species in California, and some are beneficial predators of other insects while many like BMSB are pests that can damage plants.
Caterpillars often lay eggs in large clusters on leaves, but armyworm eggs are laid in fluffy masses on the crowns of seedlings or leaves of older plants. The fuzzy egg mass pictured here belongs to the beet armyworm, a pest of many types of vegetables. They feed on seedlings, can skeletonize leaves, and gouge holes in fruits.
While not yet found in California, the egg masses of the invasive spotted lanternfly are easily recognized, occurring in groups of 30 to 50 eggs covered in a gray, mud-like covering. It's important to know what these eggs look like as they can easily be transported to new areas on firewood, building materials, trailers, and other flat surfaces.
Greenish blisters under the surface of leaves can indicate the presence of glassy winged sharpshooter's eggs, an invasive pest that is found mostly in southern California. Females lay egg masses in groups of 8 to 12 eggs arranged side-by-side under the epidermis of the lower leaf surface of young, fully developed leaves. Shortly after the eggs hatch, the leaf tissue surrounding the egg mass begins to turn brown and remains as a permanent brown scar. Glassy winged sharpshooters can transmit several important, often fatal, plant diseases in California.
Praying mantid (or mantis) eggs are laid in masses attached to twigs, fences, or other surfaces. Egg masses are frothy and pale when first laid, then dry to a brown, hardened, paper-like material. The egg case pictured here belongs to the Carolina mantid, Stagmomantis carolina, which isn't found in California, but several other species are. Mantids feed on any insects or spiders they can catch, including both pests and beneficials.
The brown, cylindrical eggs of all three species of leaffooted bugs are laid end-to-end in a string-like strand. They are often found along a stem or leaf midrib but may sometimes be found on fruit or other surfaces, as seen in this picture. Most egg masses have 10-15 eggs, although strands of more than 50 have been reported. Leaffooted bugs feed on many types of plants but damage occurs primarily when they feed on fruit or nut crops.
We hope you enjoyed this year's insect Easter egg hunt. Check back next year to test your insect egg identification skills!
/table>/table>- Author: Mackenzie Faith Patton
The invasive pest spotlight focuses on emerging or potential invasive pests in California. In this issue we are covering West Nile virus.
West Nile Virus Facts
West Nile virus disease was first reported in California in 2003 and has become the most common and serious vector-borne disease in California. With the exceptionally wet weather in 2023, reported cases of this mosquito-borne virus doubled compared to the previous year.
West Nile virus is spread by mosquitoes in the genus Culex. Usually, the virus passes between mosquitoes and birds, but mosquitoes can also transmit the virus to humans, horses, and other domestic animals.
Because mosquitoes can get the virus from birds, monitoring bird populations and recording dead birds is one of the most important ways to track this disease.
What can you do?
The best way to prevent the spread of West Nile virus is to reduce mosquito populations through controlling the mosquito larval stages. Whenever possible, standing water should be drained, since mosquito larva can grow in as little as a few ounces of water. Clean gutters and storm drains to ensure water does not collect there. In areas that cannot be drained or mosquito-proofed, such as ponds, neglected pools, or unsealed rain barrels, there are some biocontrol options like Bacillus thuringiensis (Bt) that can reduce mosquito populations. In addition to these preventative measures, protect yourself from adult mosquito bites by using mosquito repellents or wearing long-sleeved shirts and long pants.
For more information on mosquito control and protecting yourself from mosquito-borne diseases, visit the UC IPM pages on mosquitoes. To report dead birds and view more information on West Nile in California, visit Westnile.ca.gov.
[Originally featured in the Spring 2024 edition of the Home & Garden Pest Newsletter]
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- Author: Karey Windbiel-Rojas
After all the winter rains you may find yourself dealing with weeds and struggling to control them. The first step in successfully controlling weeds is knowing what weed you have. Well, you're in luck: the UC IPM website contains many useful resources to help you identify and manage weeds in the garden or landscape.
A great place to start is the Weed Gallery, which contains images and identification tips for more than 150 common weeds.
If you think you know the name of your weed, you can use the common or scientific name to view photos to confirm identification. Just use the “List of All Weeds” link from the main weed gallery page.
If you don't know what the weed is, the gallery will help you identify the plant using visual characteristics. First, narrow your search by choosing “identification” in the weed category—broadleaf, grass, sedge, or aquatic plant. That will show you a collection of photos in that category.
Select the photo of the plant form or leaf characteristic that resembles your weed (Figure 1) to see another sub-menu of weeds that exhibit more traits of your weed. Scrolling over a thumbnail image on this sub-menu will bring up several photos of the weed—as a seedling and mature plant, its flower, and seeds—to further help you identify it.
Once you think you've identified the weed, click on the linked weed name, which will take you to a photo gallery page. Here you will find details about the weed's habitat, growth characteristics, and life stages. For many weeds, there is a link to the Pest Notes that will give you information about its management, both chemical and nonchemical. Each page in the gallery also links to the Calflora website to show where the weed grows in California.
The gallery contains other features as well:
- Want to know more about plants and their parts? Illustrated tutorials distinguish among broadleaf, grass, and sedge plants and define plant parts used in characterizing certain plant species.
- Need to find out what weeds are in your lawns? The broadleaf and grass categories link to an identification key for common turf weeds.
- Didn't find your weed? See the weed identification tool under “More information” to search the UC Weed Research & Information Center (WRIC) technical weed key.
You can find the weed gallery page on the left-hand column of the main Home & Landscape page on the UC IPM web site or from the many weed-related pages. To access the weed gallery directly, visit https://ipm.ucanr.edu/PMG/weeds_intro.html.
Visit UC IPM's Weeds library page to find general weed management tips, individual weed-related Pest Notes, the weed gallery, key to weeds in turf, and other useful resources. https://ipm.ucanr.edu/PMG/menu.weeds.html
[Originally featured in the Spring 2024 edition of the Home & Garden Pest Newsletter]