Milkweed bugs gained the nickname of "seed eaters" for primarily eating the seeds of milkweed.
Actually, they are opportunistic and generalists, says Hugh Dingle, emeritus professor of entomology at the University of California, Davis.
They will eat monarch eggs and larvae (milkweed is the host plant of monarchs), as well as the oleander aphids that infest the milkweed.
We recently watched a large milkweed bug (Oncopeltus fasciatus) munch oleander aphids on a narrow-leafed milkweed (Asclepias fascicularis) in our pollinator garden in Vacaville, Calif. Between the milkweed bugs and the lady beetles, aka ladybugs), they absolutely cleaned off all the aphids, the first time in years.
Milkweed without aphids? Unbelievable! That's like macaroni without cheese, a pencil without paper, or a hammer without a nail. It's a "given" that if you grow milkweed, you'll get aphids. Some monarch butterfly enthusiasts kill the aphids with a soapy water mixture (which we've done in the past), but this year, we let biocontrol reign.
It worked wonderfully!
"Milkweed bugs will get protein from wherever they can find it," says Dingle, an insect migration biologist and author of the textbook, Animal Migration: the Biology of Life on the Move. They've been known to feed on insects trapped in the sticky pollen of the showy milkweed (Asclepias speciosa). And on nectar.
Dingle served as a professor at UC Davis Department of Entomology from 1982 to 2002, achieving emeritus status in 2003. National Geographic featured him in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on“Why Do Animals Migrate?”
A fellow of the American Association for the Advancement of Science and the Animal Behavior Society, Dingle has done research throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia.
Dingle is a former secretary of the International Society for Behavioral Ecology and past president of the Animal Behavior Society. He received the Edward A. Dickson Professional Award in 2014 to do research on "Monarchs in the Pacific: Is Contemporary Evolution Occurring on Island Islands? (See news story on Department of Entomology and Nematology website.)
Have you ever seen the larva of a lady beetle (aka ladybug) dining on an aphid?
Lights! Camera! Action!
So here is this charming little immature lady beetle chowing down on an oleander aphid that has the audacity to infest the milkweed in our pollinator garden. Chomp! Crunch! Slurp! And then another aphid arrives on the scene. It does not flee. Aphids are not the smartest of insects.
Can you just wait! Hold on! I'm not finished eating this one, yet!
And then an adult lady beetle arrives. She ignores a fat aphid right before her very eyes. Shall we prey?
Can you just wait! Don't go away! I'll eat you when I'm hungry!
A lady beetle (it's not a bug, it's a beetle!) belongs to the family Coccinellidae. Scientists have described about 5000 species worldwide, and about 450 in North America.
How many aphids can a lady beetle eat in her lifetime of three to six weeks? An estimated 5000 aphids, according to the University of Kentucky Cooperative Extension Service.
That's great pest control!
One thing is for sure: the lady beetles and their offspring patrolling our milkweed plants will never experience famine. This is an all-you-can-eat buffet, and the aphids just keep on a'coming. They do not flee. Aphids are not the smartest of insects.
Now, where are the monarchs? We have milkweed waiting./span>
Especially those oleander aphids that suck the very lifeblood out of our milkweed plants that we're struggling to save for monarch butterflies.
Just call aphids "The Enemy of the Gardener" or "The Enemy of the Milkweed."
The University of California Statewide Integrated Pest Management Program (UC IPM) describes aphids as "small, soft-bodied insects with long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids. Almost every plant has one or more aphid species that occasionally feed on it."
"Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on," UC IPM tells us. "A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface. Most species have a pair of tubelike structures called cornicles projecting backward out of the hind end of their body. The presence of cornicles distinguishes aphids from all other insects.
"Generally adult aphids are wingless, but most species also occur in winged forms, especially when populations are high or during spring and fall. The ability to produce winged individuals provides the pest with a way to disperse to other plants when the quality of the food source deteriorates."
Not only do aphids stunt plant growth but they can spread viruses. Plus, they produce that sticky honey dew they that attracts ants and other insects.
Density? We've seen aphids so dense on our milkweed stems that all we see is yellow. (Sometimes we see red!)
We recently saw them magnified on a Leica DVM6 microscope, operated by Lynn Epstein, UC Davis emeritus professor of plant pathology, at a demonstration in Hutchison Hall. (See image below)
In California, most aphids reproduce asexually throughout most of the year, according to UC IPM. Did you know that a single aphid can generate as many as 12 offspring a day--without mating?
Bring on the lady beetles (aka lady bugs), lacewings, and soldier beetles! The larvae of lady beetles and syrphid flies also do their part in gobbling up aphids.
What to do when biological control doesn't work that well? Or when your lady beetles depart? Pinch the aphids; spray them with with water; or spray them with a mixture of 1 tablespoon of dish soap (Castile liquid soap) and one quart of water. Some folks dab aphids with cotton swabs dipped in isopropyl (rubbing) alcohol but that will kill the monarch eggs and larvae as well. We've found that spraying a mixture of sudsy soap and water works best for us.
Lather is the best medicine.
We're not the only ones "celebrating" the first week of spring. The oleander aphids are doing a happy dance on our milkweed plants. We think they're doing a mixture of the tango, cha-cha-cha, salsa and merengue. Every time we walk past them, we see a population explosion with even more incredible dance moves. In population size, they went from a family reunion to an army of aphids to an international conference. Y'all come.
These are yellow, pear-shaped insects, about 1.5 to 2.6mm long, with black cornicles. They congregate on the tender young shoots and suck the very life out of them.
Now it's our job to suck the very life out of the aphids before the monarch butterflies return. There are many ways to do this. We sometimes pick them off, squishing them between our fingers. Or we invite lady beetles (aka ladybugs) and soldier beetles to pick them off--but sometimes they're not around to accept our invitations.
Actually we prefer to wash their mouths out with soap. Fill a spray bottle with a gallon of water, add a teaspoon of liquid dishwasher and spray away. The aphids are goners. Some folks add a pinch of cayenne pepper for good measure. Probably makes them more lively when they dance the salsa?
Today when we checked our milkweeds, the population had dwindled down to one aphid. Just one. A one-delegate conference with no flashy moves. It takes two to tango.
For information on how to control aphids, check out the UC Statewide Integrated Pest Management Program's website.
For information on rearing monarchs, including recommended ways to rid your milkweed of those pesky aphids, these Facebook pages are quite helpful:
The Beautiful Monarch
Public group administered by Holli Webb Hearn
"The Beautiful Monarch group was created to teach members how to raise and properly care for the monarch butterfly from egg to flying adult along with learning about their predators, diseases and other monarch facts. It is my hope that as a collective group we will help and teach one another along with any new members that join us."
Raising Butterflies and Moths for Conservation (+All Pollinators)
Closed group monitored by Mona L. Miller (apply to join)
"Our focus is the preservation and protection of North American butterflies, moths and pollinators, particularly the Monarch Butterfly.")
Sometimes in a world of towering skyscrapers, jumbo jets and warehouses big enough to hold a small planet--or at least a state the size of Rhode Island--we don't realize how “small” small is.
Last weekend it was a veritable insect feast on our narrowleafed milkweed. We saw lady beetles feeding on the oleander aphids, the oleander aphids sucking the very life out of the plant (plant juices) and monarch caterpillars polishing off the leaves.
Then the aphids started crawling on the ‘cats, and a whole new perspective of "small" burst into view.
An aphid, at about 1.5mm, is just a little larger than a pinhead. The lady beetle ranges from 0.3 to 0.4 inches (8 to 10 mm), while the monarch caterpillar, depending on the instar, is absolutely huge in comparison. Spell that H.U.G.E. According to MonarchWatch.org, the 1st instar is 2-6mm; 2nd instar, 6-9mm; 3rd instar, 10-14mm; 4th instar, 13-25mm; and 5th instar, 25-45mm.
With two handheld cameras (a Nikon D800 with a 105 macro lens and a Canon EOS 7D with an MPE 65mm lens), we managed to grab a few photos of a tiny aphid crawling on the caterpillar's head, body and tentacle.
That's how "small" small is.