Which one is the most popular? Initially, it was the tropical milkweed, A. curassavica. We collected the first five caterpillars there. The A. fascicularis yielded the rest.
So, the count: narrowleaf milkweed, 11; tropical, 5; and showy, a no-show.
To date this year, we have released six monarchs back into the garden. The others went for university research. Elizabeth Pringle's laboratory at the University of Nevada, Reno, needed male and female monarchs to rear a colony, and the UC Davis laboratory of Louie Yang needed some tachinid flies.
Unfortunately for us--and fortunately for the Yang lab--tachinid flies infested two of our "11-piece collection." The adult flies are parasitoids that lay their eggs in immature monarchs (among other hosts). The fly larvae hatch and eat their host from the inside out. In a chrysalid, you can tell a tachnid fly infestation by the large tell-tale "dented" brown spot, it looks somewhat like a rotten spot on an apple. In a caterpillar? Think withered and discolored. Then a bungee-like white string appears, and the larvae (maggots) slide down--probably gleefully--like a kid on a Goliath Slide at the county fair.
Tachinids, however, are considered beneficial insects. They lay their eggs in or on such pests as cabbage loopers, cutworms, cabbage worms, gypsy moths, hornworms, harlequin bugs, lygus bugs, cucumber beetles, earwigs and the like. (See Bug Squad blog for close-up images of the tachinid larvae and pupae.)
2016: A Very Good Monarch Year
The year 2016 was a very good year for monarchs in our pollinator garden; we reared and released 60-plus. Sadly, the numbers fell drastically in 2017, 2018 and 2019. Last year, no eggs, no caterpillars and no chrysalids, and only a few monarchs passed through. In fact, in 2019 we did not see our first monarch until Aug. 9.
This year we're noticing a comeback of sorts. We spotted the first monarch on May 24. We now see:
- Males patrolling our yard and chasing the females--morning, noon and evening
- Females laying their eggs on the narrowleaf milkweed that's beneath the honeysuckle vine or the tropical milkweed that's beneath the roses
- Both males and females nectaring on milkweed, butterfly bush (Buddleia davidii), and Mexican sunflower (Tithonia rotundifolia), napping in the branches of the cherry laurels, and greeting any guests with flutter fanfare.
Life is good.
Sometimes the Gulf Fritillaries, Agraulis vanillae, that are hanging out on their host plant, the passionflower vine, mistake them for one of their own species and a pursuit begins.
Yes, the predators are out there: the California scrub jays, praying mantids, spiders, European paper wasps and yellow jackets. So are the tachinid flies and parasitoid wasps.
Would it be too much to ask them to...um....leave our monarchs alone? Yes.
Everybody eats in the garden. The menu choice is theirs.
If you've ever stepped in sticky gum, it's similar to what happens when an insect steps into milkweed pollinia.
Take the wasps visiting the tropical milkweed (Asclepias curassavica) on Thursday morning, July 16 in the UC Davis Arboretum and Public Garden.
They foraged on the colorful red, yellow and orange blossoms, and as nature intended (for reproductive reasons), flew off with that sticky pollinia from the anthers.
Basically, pollinia is a sticky packet of golden pollen grains originating from a single anther. The wishbone-shaped pollinia are in a nectar trough where insects often get trapped. Some insects manage to escape but leave body parts behind. A foot here...a wing there...an antenna over there...
One wasp exited a flower with "the golden glue" on its feet.
“Too funny with all the milkweed pollinia all over its feet,” commented Lynn Kimsey, director of the Bohart Museum of Entomology and Nematology and professor of entomology at UC Davis, who identified the wasp as a species of Podalonia, parasitoidal wasps in the family Sphecidae. "It looks like it's wearing fluffy socks.”
We've seen honey bees on showy milkweed (Asclepias speciosa) struggling to free themselves, only to find the bees dead the next day--and new recruits buzzing in for their share.
These Podalonia wasps, however, managed to navigate the "traps" quite well.
They'll be back for another round.
(Reminder: Folks planting the tropical milkweed in temperate zones (like here in Davis, 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.)
A pollinator garden is a study in diversity--and of inclusion and exclusion.
The residents, the immigrants, the fly-bys, the crawlers, the wigglers, the jumpers. The big, bad and bugly. The prey and the predators. The vegetarians and carnivores.
The nectar-rich flowers attract honey bees, bumble bees and butterflies. And right near them are the predators: the praying mantids, dragonflies and assassin bugs.
The assassin bugs, family Reduviidae, are ambush predators. They resemble human assassins (or at least those on the movie screen!): long narrow neck, beady eyes, and sturdy body. When they ambush a predator, they stab it with their rostrum, inject venom, and suck out the juices. Or as UC Berkeley entomologists Jerry Powell and Charles Hogue write in their book, California Insects, "The victims, which include all kinds of insects, are snatched by quick movements of the forelegs, and immediately subdued by a powerful venom injected through the beak."
Such was the case with the assassin bug, Zelus renardii, this week. We watched one lie in wait on a Mexican sunflower (Tithonia); we watched another dine on an unidentifiable prey on a milkweed blossom; and we watched yet another stab a lady beetle (aka lady bug) on a leaf.
Everybody eats in the pollinator garden.
We never thought we'd see one this year.
And then it arrived.
The first monarch sighting of the year.
A Danaus plexippus majestically touched down on our Mexican sunflowers (Tithonia) around 5 this afternoon in our pollinator garden in Vacaville, circled the milkweed plants about 10 times, and then fluttered over the roof and vanished.
Meanwhile, we managed to grab a couple of photos of the iconic butterfly.
Fellow monarch enthusiasts report the scarcity of monarchs.
"Haven't see any this year," said one.
"Me, either," said another.
"No, not a single one," said yet another. "I'm looking."
Rita LeRoy has seen two at the Loma Vista Farm, Vallejo.
"Send some over to us," we said.
We remember butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, commenting at a meeting hosted at UC Davis Feb. 28, 2019 by the Environmental Defense Fund, that "monarchs are on life support." The attendees--some scientists, some citizen scientists--were there to discuss "Recovering the Western Monarch Butterfly Population: Identifying Opportunities for Scaling Monarch Habitat in California's Central Valley."
The organizers related that "The latest population surveys indicate that monarchs overwintering on the central coast have declined 86% since last winter and now total 0.5% of their historical average. Population declines have spurred greater scientific study, funding, and coordination around the western monarch. California legislators appropriated $3 million in funding to the CA Wildlife Conservation Board to establish the Monarch Butterfly and Pollinator Rescue Program."
"Additionally," they said, "the Western Association of Fish and Wildlife Agencies released a Western Monarch Butterfly Conservation Plan calling for an additional 50,000 acres of monarch-friendly habitat in the California Central Valley and adjacent foothills by 2029. Join Environmental Defense Fund along with farmers, restoration practitioners, and scientists for an invitation-only workshop to share expert knowledge and identify strategic opportunities for restoring monarch butterfly habitat across the Central Valley. We will discuss important topics including opportunities for monarch habitat in the food production landscape, incentivizing monarch habitat restoration using limited resources, production and distribution of native plants, and other subjects that will put the western monarch butterfly population on the path to recovery. We will use the results of the workshop to inform conservation initiatives and effectively and efficiently allocate funds and resources for optimal conservation outcomes."
Shapiro was one of the five speakers in the "State of the Science" workshop section. He has been monitoring Central Valley's butterfly population since 1972 and maintains a website on his research.
In his presentation, Shapiro declared that "monarchs are on life support in California, and we are reduced to prescribing placebos."
"Consider a doctor faced with a patient in rapid decline," Shapiro told the group. "All tests have failed to identify the cause. What is the doctor to do? You can't prescribe treatment for an undiagnosed illness, can you? You can make a wild stab at a prescription on the basis that the patient is going to die anyway, and MAYBE, just maybe, this drug will do some good. Or you can prescribe a placebo, just to reassure the patient that you are doing something. That's where things get interesting. Occasionally a patient improves drastically on a placebo. Maybe he would have improved anyway; there's no way of knowing. Suppose our patient has a complete remission despite having received only a placebo. Does our doctor convince himself the placebo cured him? As of right now, the Monarch is on life support in California, and we are reduced to prescribing placebos. If our patient comes back from the brink—as history suggests it may well—will we convince ourselves that our placebos worked? Probably. And that's not how to do science. That's what philosophers call the fallacy of post hoc, ergo propter hoc. We can do can do better than that!" (Read his presentation on a Bug Squad blog.)
Meanwhile, we know there's at least one monarch in Vacaville...Maybe it's a female and will return to lay eggs on our milkweed. We can only hope.
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>