It sucks sap, it secretes honeydew, and it draws ants.

And curious photographers.

Last weekend we spotted cottony cushion scale, Icerya purchasi, infesting the twigs and branches of our Nandina (Nandina domestica), planted 22 years ago. This scale insect is more commonly found on citrus crops and Pittosporum, but there it was.

It's a native of Australia and apparently made its way to California on acacia plants around 1868 or 1869, and began infesting citrus groves in southern California. It's now found throughout the world, wherever citrus is grown. Pick it up and it's as light as a feather and soft as cotton. 

If you look closely at a mature cottony cushion scale (hermaphrodite), you can see that it's reddish brown with black hairs. It produces a ridged white egg sac encasing hundreds of brilliant red eggs--the color of pomegranate kernels. 

The UC Statewide Integrated Pest Management Program (UC IPM) says it's easy to spot. Yes, it is, especially when it's looks like drops of snow on cherry-red Nandina berries. 

"Like other scales, cottony cushion scale decreases the vitality of its host by sucking phloem sap from the leaves, twigs, branches, and trunk," according to UC IPM. "Feeding can result in defoliation and dieback of twigs and small branches when infestations are extremely heavy. Heavy populations can severely reduce the yield of citrus trees. Like soft scales, cottony cushion scale excretes honeydew, which is usually accompanied by blackish sooty mold growth and ants."

 "Cottony cushion scale has two to three generations a year," UC IPM tells us. "Unlike most other scales, it retains its legs and its mobility throughout its life. Cottony cushion scale completes its life cycle in three months during warm weather conditions."

Its most famous natural enemy is the vedalia beetle, Rodolia cardinalis, introduced from Australia in the 1890s to save California's citrus crops. Vedalia beetle vs. cottony cushion scale--this is a clear-cut case of successful biological control. Vedalia beetles are distinguished by their darker red domes with splotchy black markings.

Another natural enemy is the parasitic fly Cryptochaetum iceryae, which lays its eggs inside the cottony cushion scale. "It deposits one to four eggs inside each second-instar, third-instar, or adult female scale body," UC IPM points out. "The eggs hatch into larvae that feed within the scale." (See more information on the UC IPM website)

Interesting that we've never found the cottony cushion scale on our nearby tangerine and lemon trees. "Marked Safe from Cottony Cushion Scale." 

For now!

It's Friday Fly Day--and time to post images of a syrphid fly.

Syrphid flies, often mistaken for honey bees, are pollinators, too. 

Also known as flower flies and hover flies, syrphids hover over a flower before touching down. "Most species are predaceous, most commonly on aphids or mealybugs," according to the UC Statewide Integrated Pest Management Program. "Some syrphids prey on ants, caterpillars, froghoppers, psyllids, scales, other insects, or mites. About 100 to 400 aphids can be fed upon by each aphid-feeding larva before it pupates, but this varies by the mature size of the syrphid relative to the aphids' size."

They are easily distinguished from honey bees because (1) bees don't hover, and (2) syrphids have only one pair of wings, while bees have two. "Their large eyes and short antenna also give them away, notes Kelly Rourke in a U.S. Forest Service article on "Syrphid Fly (Sphaerophoria philanthus). The absence of pollinium, or pollen sacs, is more difficult to see, but is another difference from a bee. Of the nearly 900 species of flower flies (family Syrphidae) in North America, most have yellow and black stripes."

Several years ago we captured images of a syrphid fly and an Asian lady beetle (Harmonia axyridis) on a rose bush in our Vacaville pollinator garden.

The scenario: Aphids were sucking plant juice on one end and secreting honey dew on the other end. The lady beetle was feasting on the aphids and getting sticky from all that honey dew.

Then along came a syrphid, a female Scaeva pyrastri, as identified by senior insect biosystematist Martin Hauser of the Plant Pest Diagnostic Branch, California Department of Food and Agriculture. It hovered over the lady beetle and then dropped down to lick the honey dew from the beetle's head.

'Twas a happy day for the lady beetle and the syrphid fly, but not so much for the aphids. 

You know those dratted aphids, those little pests that suck the very lifeblood out of your prized plants?

Well, have you ever watched them give birth?

They do, you know. Live births.

The UC Statewide Integrated Pest Management Program says that "Aphids have many generations a year. Most aphids in California's mild climate reproduce asexually throughout most or all of the year with adult females giving birth to live offspring—often as many as 12 per day—without mating."

"Because each adult aphid can produce up to 80 offspring in a matter of a week, aphid populations can increase with great speed."

We've captured a few images of aphids giving birth in our Vacaville pollination garden...but only with the microscopic-like Canon MPE-65mm lens (mounted on an EOS 7D). If you think aphids are tiny, their babies are super tiny.

Videos, however, tell the story better. Check out the KQED Deep Look video Born Pregnant: Aphids Invade with an Onslaught of Clones.

As we mentioned in a previous Bug Squad blog, UC Cooperative Extension specialist and agricultural entomologist Ian Grettenberger of the UC Davis Department of Entomology and Nematology faculty, assisted with the KQED Deep Look video, which won a nature award equivalent to an Oscar. 

Grettenberger provided his expertise--and some aphids--working with digital video producer Josh Cassidy, senior video producer for KQED Science and the lead producer and cinematographer for Deep Look, a short-form nature series that illuminates fascinating stories in the natural world. The video scored an international Jackson Wild Media Award, winning first place in the category, "Animal Behavior, Short Form video (17 minutes or less)."

The Deep Video points out that the aphids are highly skilled at "making babies."

Yes, they are. 

Fortunately, we have lady beetles (aka ladybugs) and soldier beetles that are highly skilled at eating them! 

If you love tomatoes, you probably hate hornworms.

Frankly, the garden's not big enough for both of you, and one of you has to go. It's not you. It's the hornworm.

"This one is nobody's friend if you're a gardener and like to grow tomatoes," says entomologist Jeff Smith, curator of the Bohart Museum of Entomology's Lepidoptera collection,  in his recently posted video showcasing the hornworm and its adult form, the sphinx moth (Sphingidae family).

Smith is presenting a series of short videos on the "different aspects of the collection of moths and butterflies."

In this video, Smith relates how the hornworm got its name: There's a "horn" at the end of its abdomen that looks like "a little spike."  The tobacco hornworm (Manduca sexta) and tomato hornworm (Manduca quinquemaculata) are quite similar, he points out. Both are pests on tomatoes and are often labeled as "tomato hornworms."

The origin of the name, the sphinx moth? "When the larva or caterpillar is disturbed, it rears up into an Egyptian sphinx-like pose," Smith says. 

However, good luck finding hornworms. "They are so well camouflaged, that it takes forever to find them," Smith says. One way to know they're there is "because they make a piece of poop (frass) about as big as a pea," Smith says.

When the caterpillars are attacked, "they spit tomato juice on you, which doesn't taste good."

The UC Statewide Integrated Pest Management Program (UC IPM) says this about hornworms: "Hornworms feed on blossoms, leaves, and fruit. At high populations they can extensively defoliate plants and scar the fruit. They are rarely a problem in the warmer interior valleys unless natural enemies are disrupted, in which case, they can do serious damage. They are mostly problems in garden situations."

UC IPM points out that "The adult moth is a strong flier with a wingspan up to 5 inches (12 cm). Development takes about 2 months in summer; the winter is passed in the pupal stage. There are two generations a year in most areas; larvae are usually most common in midsummer, but there may be a small population peak in late summer. Infestations tend to be more severe in warm inland areas." (Read more UC IPM information here.)

The Bohart Museum of Entomology also offers online information sheets, the work of Lynn Kimsey, director of the Bohart and a UC Davis distinguished professor of entomology. (The directory of subjects is here.)

"The larval stage (caterpillar) feeds primarily on tomatoes, but it also is known to attack other crop plants in the Solanaceae, including egg plants, peppers, and potatoes," Kimsey noted. "When the caterpillars are numerous, they can do extensive damage in a short time. The caterpillars feed on the upper portions of leaves and new stems, and occasionally, when the caterpillars are numerous, it will feed on the tomato fruit as well. They tend to remain out of direct sunlight, and so are found near the main stem of the plant during the day. They are more easily spotted when they move to the outer portions of the plant at dusk and dawn. Their presence is often first recognized by an excessive amount of frass (droppings) around the base of the plant. The hornworm caterpillar is 3½-4 inches (9-10 cm) long and pale green, with white and black markings." (Read more about the Bohart Museum's information on hornworms here.)

Meanwhile, have you ever been up close and personal to a hornworm?

We don't have any in our garden, so we borrowed a hornworm from a neighbor whose garden thrives with tomatoes and peppers. She plucked it off a pepper plant. "It seems to like the pepper plant better than the tomato," she said. 

Perhaps this one will grow to adulthood? Apparently it's a tobacco hornworm as it has a red-tipped horn. "Tomato hornworms have eight V-shaped white markings with no borders; tobacco hornworms have seven white diagonal lines with a black border. Additionally, tobacco hornworms have red horns, while tomato hornworms have dark blue or black horns," according to Wikipedia. The tobacco hornworm turns into a Carolina sphinx moth or, generally, a hawk moth. The tomato hornworm turns into a sphinx moth commonly known as a sphinx, hawk, or “hummingbird” moth.

(Editor's Note: The Bohart Museum, located in Room 1124 of the Academic Surge Building on Crocker Lane, UC Davis, is the home of nearly eight million insect specimens; a live "petting zoo," comprised of Madagascar hissing cockroaches, stick insects and tarantulas; and a gift shop. The Bohart is temporarily closed due to the COVID-19 pandemic precautions but the gift shop is online.)