If you engage in social media, you've probably seen a "what-is-this" query about a spider that some unsuspecting person discovered quite unexpectedly in a garden, bedroom, bathroom or garage. Triple exclamation points usually accompany "Yecch!!!" (Expletives usually require quadruple exclamation points.)
For a good general view of spiders, check out the UC Statewide Integrated Pest Management Program's newly revised "Spiders" Pest Note.
"Many people fear or dislike spiders," according to the site, but "for the most part, spiders are beneficial because of their role as predators of insects and other arthropods, and most cannot harm people. Spiders that might injure people—for example, black widows—generally spend most of their time hidden outside homes in woodpiles or in clutter in the garage. The spiders commonly seen out in the open during the day are unlikely to bite people."
Spiders, which are arachnids, differ from insects in that they have eight legs (not six) and have no wings or antennae.
UC IPM offers information on black widow spiders, yellow sac spiders and recluse spiders (which, contrary to popular opinion, are NOT found in California). The website also touches on jumping spiders, hobo spiders, common house spiders, and tarantulas. A table, illustrated with photos, lists the common spider families in North America, including:
- Agelenidae, funnel weavers or grass spiders
- Araneidae, orb weavers or garden spiders
- Clubionidae (including Corinnidae), sac spiders or twoclawed hunting spiders
- Linyphiidae (=Microphantidae), dwarf spiders
- Lycosidae, wolf spiders
- Oxyopidae, lynx spiders
- Salticidae, jumping spiders
- Theridiidae, cobweb, cobweb weaver, or combfooted spiders
- Thomisidae, crab spiders or flower spiders
What about spider bites? "Unlike mosquitoes, spiders do not seek people in order to bite them," UC IPM says, tongue in cheek. "Generally, a spider doesn't try to bite a person unless it has been squeezed, lain on, or similarly provoked to defend itself. Moreover, the jaws of most spiders are so small that the fangs cannot penetrate the skin of an adult person. Sometimes when a spider is disturbed in its web, it may bite instinctively because it mistakenly senses that an insect has been caught."
If you've got a hankering to see a live tarantula (who doesn't?), you can do so when the Bohart Museum of Entomology at UC Davis opens its doors again to the public. The Bohart Museum, home of nearly eight million insect specimens, a gift shop (now online), and a live "petting zoo" (think Madagascar hissing cockroaches, walking sticks and taranatulas) is located in Room 1124 of the Academic Surge Building on Crocker Lane. UC Davis spider expert Professor Jason Bond and his lab usually present a program there at least once a year or engage with folks at the open houses. Bond serves as the Evert and Marion Schlinger Endowed Chair in Insect Systematics, UC Davis Department of Entomology and Nematology. (See his lab website)
As an aside, Professor Bond "bonds" with spiders. Yes, he does. And he's never met a spider he didn't like.
Have you ever seen a plume moth?
Or has a plume moth ever seen you?
We spotted a pterophorid plume moth (family Pterophoridae) yesterday on our back door in Vacaville, Calif. The t-shaped moth stayed in the same spot the entire day, from dawn to dusk, even when we entered and exited the door multiple times.
Its shape is what makes it unusual. Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, told us awhile back that the "T-square shape is classic."
In some respects, the pterophorid plume moth is fit to a "T."
At rest, the plume moth holds its slender wings at right angles to body, giving it a T-shaped profile.
In his book, California Insects, UC Berkeley entomologist Jerry Powell (now emeritus) explains why they're called plume moths..."because the forewings are deeply notched and the hindwings are divided into three linear parts, each with long scale fringes. When perched, the insects roll the forewings around the folded hindwing plumes, resulting in peculiar sticklike or craneflylike appearance, unlike any other moth."
Most are nocturnal and are attracted to lights, Powell adds. (Like porch lights!)
Its ancestors lived millions of years ago. Wikipedia tells us that a fossil species from the extant genus Merrifieldia originates from the Oligocene of France. The Oligocene, a geologic epoch of the Paleogene Period, occurred 33.9 million to 23 million years ago. Today some 160 species of plume moths live in North America.
So why did the plume moth visit us? Well, it's a common moth. The adults feed on nectar and pollen (plenty of that in our pollinator garden) and caterpillars of some of the species chew the leaves of garden plants, including geraniums and snapdragons (we have both).
We also have artichokes, and the larvae of one species, the artichoke plume moth, can be a pest when the vegetable is grown as a perennial, according to the UC Statewide Integrated Pest Management Program website.
One thing is for sure: once you see the plume moth, you'll always recognize it.
"Eat your greens," they say.
Okay, we don't need any encouragement, but apparently many other folks need a push, a poke or a prod to eat cole crops, including cabbage, cauliflower, Brussels sprouts, broccoli, mustard, kale and kohlrabi.
Well, cabbage aphids need no encouragement. We spotted some dusty blue-gray aphids, Brevicoryne brassicae, slurping the very life blood out of our mustard plants yesterday in Vacaville, Calif. That's what they do, and they do it well, thank you.
Frankly, we're so accustomed to seeing green and yellow aphids, that the blue-gray colors are sort of a treat. Sort of. But they are a pest. These European natives can and do cause significant yield losses to cole crops (mustard family, Brassicaceae).
And they are not social distancing.
The UC Statewide Integrated Pest Management Program (UC IPM) says: "They commonly occur in dense colonies, often covered with waxy droplets. They prefer to feed on the youngest leaves and flowering parts and are often found deep within the heads of cabbages or Brussels sprouts. The aphid has a simple life cycle with adult females giving birth to live offspring throughout the year in most parts of California. Both winged and wingless adults occur; the winged adults have a black thorax and lack the waxy coating. The aphid does not infest noncruciferous crops but can survive on related weed species when cole crops are not in the field."
UC IPM goes on to say that "Important natural enemies include lady beetles, syrphid fly larvae, fungal diseases, and the parasitic wasp, Diaeretiella rapae."
Nary a lady beetle (aka ladybug) in sight--but a syrphid (aka flower fly or hover fly) just landed.
It's a strikingly beautiful insect.
But in its larval stage, the alfalfa butterfly, Colias eurytheme--also known as the orange sulphur butterfly--is a pest.
If you grow alfalfa, you're not a fan of this butterfly, and rightfully so.
"Alfalfa caterpillars can consume entire leaves," according to the UC Statewide Integrated Pest Management Program (UC IPM) website. "The larger larvae are most destructive."
The butterfly lays its eggs "on the new growth of alfalfa that is less than 6 inches tall," UC IPM says. "Eggs hatch into green caterpillars in 3 to 7 days. Full-grown caterpillars are about 1.5 inches long and are distinguished from other caterpillars on alfalfa by their velvety green bodies with white lines along their sides."
"Caterpillar populations usually result from a flight of butterflies into the field when the alfalfa is less than 6 inches tall. Extremely large numbers of adults migrating between fields are often present from June to September in the Central Valley and from May to October in the southern desert."
We've been seeing lots of alfalfa butterflies sipping nectar on our African blue basil (Ocimum kilimandscharicum × basilicum 'Dark Opal').
Sometimes they don't notice you and you can edge toward them, camera in hand.
Sometimes they don't even notice that a honey bee is shadowing them. Honey bees are also quite fond of African blue basil.
Butterfly meet bee. Bee meet butterfly.
In the insect photography world, that's called a "two-fer"--a bonus of two insects in one photo.
Take the immature form (caterpillar) of the moth, Schizura concinna, family Notodontidae. We first spotted this caterpillar on our Western redbud tree (Cercis occidentalis) in September 2010.
It has a red hump. The common name: The redhumped caterpillar.
Art Shapiro, distinguished professor of evolution and ecology at UC Davis, told us that the red hump contains a defensive formic acid gland. "They hold their anal prolegs, which are not useful for walking, in the air and thrash their rear ends in unison when disturbed. This is the ONLY defoliator of redbud around here, and is very common. It also attacks walnut and a variety of other chemically-distinctive trees that other things don't eat, as a rule."
We wondered if these little thrashing visitors should concern us. "The damage is minor, and I strongly advise against spraying; hand-picking can be used if control is deemed necessary, but they feed so late in the season that there is no actual harm to the tree," he told us. "The moth is very nondescript. It holds its wings wrapped around the body cylindrically and looks remarkably like a cigarette butt, though it is probably 'imitating' a broken-off twig. Despite authoritative commentary to the contrary, they have two broods a year here but are usually seen in fall. The species is native on both coasts and oddly absent in most of the mid-continent."
We thought we might see redhumped caterpillars on our liquidambar (sweet gum) trees that we planted more than two decades ago. We never have.
What we did see this week is that the UC Statewide Integrated Pest Management Program (UC IPM) has revised its Pest Notes: Redhumped Caterpillar. A recent UC IPM blog described the caterpillar as a "familiar pest on fruit and nut trees such as plum, almond, cherry, and apple, as well as on ornamental trees like liquidambar and birch. It can reach high populations in California's Central Valley, sometimes defoliating entire trees."
The Pest Note, co-authored by entomologists Emily Symmes, UC IPM and UC Cooperative Extension, Sacramento Valley, and Steve Dreistadt, UC IPM, describes the pest, its life cycle, and the damage rendered. You can read about a variety of management techniques.
Ah, the redhumped caterpillar...
And if you're curious about common names and scientific names of insects, the Entomological Society of America (ESA) maintains a Common Name Database, "an essential reference for anyone who works with insects. It includes more than 2,000 common names and is searchable by common name, scientific name, author, order, family, genus, and species."
Have a suggestion for a common name? You can propose it on the ESA form. Names are reviewed by the Committee on the Common Names of Insects and voted on by the ESA Governing Board.
It's probably unlikely, however, that redhumped caterpillar, will undergo a name change any time soon. That red hump is so descriptive!