- 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
- Author: Kathy Keatley Garvey
Remember when San Francisco 49'ers wide receiver Brandon Aiyuk credited his spectacular 51-yard catch in the 2024 NFC championship game with the Detroit Lions to a ladybug (note that entomologists correctly call it a "lady beetle") landing on his shoe before the game?
Well, those attending the 110th annual UC Davis Picnic Day activities on Saturday, April 20 at Briggs Hall--home of the UC Davis Department of Entomology and Nematology--can also net some luck.
Children are encouraged to take home a couple of the beetles at the UC Statewide Integrated Pest Management Program (UC IPM) booth in the courtyard of Briggs. (Adults can do so, too. Maybe they'll name their beetles "Brandon" and "Aiyuk.")
The ladybug is actually a beetle (Coleoptera), not a bug (Hemiptera). It's associated with good luck because it eats the aphids that try to destroy our crops. It can eat as many as 5000 aphids in its lifetime, scientists estimate.
"These beetles have become a cultural icon of sorts because of their appearance and their beneficial habits," writes UC Davis distinguished professor Lynn Kimsey, former director of the Bohart Museum of Entomology, in her insect fact sheet on lady beetles. "Both adults and larvae feed on aphids and other small, soft-bodied insects...They are ferocious predators on small insects." (See what the UC Statewide Integrated Pest Management Program says about lady beetles.)
Ever seen a close-up shot of a lady beetle eating an aphid? The predator and the prey...
Ever seen a cellar spider snaring and eating a lady beetle? The predator and the predator...one becomes prey.
Ordinarily, the lady beetle's bright red coloration serves as a "warning" to predators. Plus, lady beetles are known to ooze a foul-tasting chemical that tastes so bad that predators leave them alone. This lady beetle engaged in "reflex bleeding," exuding an alkaloid toxin (which did not deter the predator).
Lady beetles will be just a few of the bugs at Briggs Hall during UC Davis Picnic Day. You'll also see cockroach races, maggot art, and displays featuring ants, bees, walking sticks, mosquitoes, nematodes, butterflies, spiders, whip scorpions, and more. Check out "bug" activities at Briggs Hall here. UC Davis Picnic Day is free and family friendly.
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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