The elm leaf beetles and their larvae don't want to hold your hand--unless perhaps you're holding a elm leaf that they can eat.
A recent walk down the 200 block of Buck Avenue, Vacaville, California, revealed the damage this pest does. The stately canopied elms don't look so stately, what with the dry skeletonized leaves, the browning and the dieback.
And if you look closer, you'll see the leaves--the feeding site--dropping prematurely, and beetles and their larvae falling with them.
Infestations of these beetles can defoliate large elm trees, according to the UC Integrated Statewide Management Program's Pest Note on this pest, Xanthogaleruca (=Pyrrhalta) luteola.
Have you ever seen them? They're about 1/4 inch long, yellow to olive-green with a black stripe on each side and four black spots near the head. They are an invasive species from southern Europe, introduced here in the 1800s, and considered the most serious elm defoliator in the United States.
"Females lay yellowish eggs in double rows of about 5 to 25 on the underside of leaves," according to UC IPM. "Eggs become grayish before hatching. Larvae resemble caterpillars and are black when newly hatched and shortly after molting (shedding the old skin). After feeding, larvae become yellowish to green with rows of tiny dark tubercles (projections). Third-instar larvae grow up to 1/3 inch long and have dense rows of dark tubercles down their sides that resemble two black stripes. Pupae are orange to bright yellow."
We observed some natural enemies on site: lady beetles, aka ladybugs, and their larvae munching on the larvae of the elm leaf beetles. Yes, beetle larvae eating beetle larvae. Lady beetles and their larvae target soft-bodied insects, and not just aphids.
UC IPM says:
"The elm leaf beetle develops through four life stages: egg, larva, pupa, and adult. Adults commonly overwinter in bark crevices and woodpiles or in buildings. In spring they fly to elm foliage and chew leaves, and females lay eggs. Eggs hatch into larvae that develop through three instars (growth stages) over a period of several weeks while chewing on foliage and then crawl down the tree trunk. Mature larvae become curled and inactive (a stage referred to as prepupae), then pupate, sometimes in large numbers, around the tree base. After about 10 days as pupae, adults emerge and fly to the canopy to feed and, during spring and summer, lay eggs. The elm leaf beetle has at least one generation a year in northern California and two to three generations in central and southern California."
Elm trees with massive defoliation can weaken the tree and pave the way for diseases and damage from other pests.
If you have elm trees, especially European elm species, and you have these little buggers all over them, you might want to access the UC IPM Pest Notes to see how to manage them.
These beetles mean business./span>
It was July 3, 2020.
The male bees, Melissodes agilis, were getting quite territorial.
Every time a butterfly, a honey bee or another insect in our family's pollinator garden expressed an interest in foraging on the Mexican sunflowers, Tithonia rotundifola, a male Melissodes buzzed them.
"Get out of here!" he threatened. "I own these flowers. These are mine!"
What to do? I grabbed my Nikon D500 and 200 mm macro lens, adjusted the settings to 1/5000 of a second, f-stop 5.6, ISO of 800, and managed to get a shot of the menacing bee confronting a bewildered monarch.
Eye-to-eye. Antenna-to-antenna. Wing-to-wing.
What happened? The monarch quickly escaped the wrath.
And the bee? It buzzed off, only to return to target another insect.
"Get out of here! I own these flowers. These are mine!"
Another tiff on the Tithonia. Another round on the rotundifola.
Just another day in the pollinator garden.
The monarch caterpillar feasting on the tropical milkweed, Asclepias curassavica, in Vacaville, Calif., kept doing what monarch 'cats do best--eat.
She insisted on devouring the leaves as if there were no tomorrow--and today would end soon.
How did we know her gender? Our Danaus plexippus pupated, formed a chrysalis, and emerged. Oh, you beautiful gal!
Folks who comment that someone is "eating like a pig" or "eating like a horse" or "wolfing it down," have probably never seen a monarch caterpillar chow down, scarf it up or shovel it in.
One minute our little 'cat is stretched out on a leaf, binge eating. The next minute the leaf is gone and she's porking out on a second leaf. And scouting for a third.
Eric Carle titled his classic children's book, "The Very Hungry Caterpillar," quite well. His little 'cat ate everything in sight: gobbling, guzzling, gorging and gulping down everything from fruits and vegetables to junk food.
Remember the story? First, the little 'cat ate an apple, two pears, three plums, four strawberries, and five oranges but was still hungry. Famished, really. So he ate a piece of chocolate cake, a lollipop, a piece of cherry pie and a cupcake...and more...and he wasn't little anymore.
Many folks sheltering at home during the COVID-19 crisis can certainly identify with the snatch-and-grab menu of "The Very Hungry Caterpillar."
Did someone say "chocolate cake?"
(Editor's Note: Those planting the tropical milkweed in temperate zones (like here in Vacaville,Calif.) must remove or cut back the tropical milkweed by winter. "A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves," explains the Xerces Society for Invertebrate Conservation.)
Yes, they do, and yes, she did.
Painted lady butterflies, Vanessa cardui, do lay their eggs on Echium wildpretii, commonly known as "the tower of jewels."
However, this little lady (below) persistently returned a few times to find a bee-free spot. She finally claimed a chunk of space near the top of the 8-foot plant.
Temporarily. Until the bees reclaimed it.
"Echium is a borage," says butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology. "Boraginaceae are one of the favored host families, so I'm not surprised."
"They routinely breed on fiddleneck and popcorn flower," Shapiro says. "in 2015 they completely destroyed the borage crop at an herb farm in Solano County!" He recently saw them lay eggs on Helianthus, Cardooon (artichoke thistle) and Lupinus succulentus.
"It's been a pretty good cardui year but not as big as last year," said Shapiro, who has monitored the butterfly population in Central California since 1972 and publishes his research on his website. "They've been coming in waves for several weeks and there are still some, mostly old females ovipositing."
Said Bohart Museum of Entomology associate Greg Kareofelas, a naturalist and insect photographer: "Vanessa cardui probably has the greatest range of host plants as any butterfly. My question always is: What plant, won't it lay eggs on?"
I call him the Mountain Boy.
A male carpenter bee, Xylocopa tabaniformis orpifex, appeared in our pollinator garden in Vacaville, Calif.,on Feb. 27, the earliest we've seen this species.
It's the smallest of California's carpenter bees and is often called the foothill or mountain carpenter bee.The females are black with light smoky-colored wings. The male has bright yellow marks on the lower part of its face and some yellow hairs on the top front of its thorax.
In addition to the mountain carpenter bee, California's species are:
- The Valley carpenter bee, Xylocopa varipuncta, the largest of the California carpenter bees. It's about an inch long. The female is solid black, while the male, commonly known as "the teddy bear bee," is a green-eyed blond. Why teddy bear? It's fuzzy and does not sting--or as the late Robbin Thorp (1933-2019) distinguished emeritus professor of entomology at UC Davis, was fond of saying: "Boy bees don't sting."
- The California carpenter bee or Western carpenter bee, Xylocopa californica, the second largest of the California carpenter bees. It's often found in the mountain foothill areas of northern and southern California. It's known for its distinctive distinctive bluish metallic reflections on the body, Thorp says. The females have dark smoky brown wings.
Look around. You may find a "mountain boy" or a "mountain girl" foraging in your yard or local park.