Chocolate midge. (Photo couresty of Brian V. Brown/Encyclopedia of Life)

These tiny flies (about 1 to 3mm) pollinate the intricate flowers of the cacao tree, Theobroma cacao. From those seed pods, known as cocoa beans, come the chocolate that we crave. In fact, we Americans consume 2.8 billion pounds of chocolate every year, or about 11 pounds per person, according to chocolatestore.com. For Valentine's Day, we purchase some 58 million pounds!

Thank you, midges!

The cacao tree thrives in parts of Central America, South America, Africa and Asia, but there's also one thriving in the UC Davis Botanical Conservatory, off Kleiber Hall Drive, UC Davis campus. You can see the "chocolate tree loaded with fruit" from noon to 4 p.m., Saturday, Feb. 16 during the eighth annual UC Davis Biodiversity Museum Day. The event showcases 13 museums or collections (see schedule for varyng times). It's a free, family friendly event, both educational and entertaining.

Ernesto Sandoval, collections manager for the Botanical Conservatory (part of the College of Biological Sciences Greenhouses, Department of Plant Biology), says the cacao tree is "upwards of 25 years old."

How does it get pollinated? "Ours gets pollinated when we spray it down with water to wash away mealybugs."

Sandoval and his staff plan to make chocolate (cocoa powder and chocolate are made from the dried seeds.) "I have just an inkling of how to make chocolate but one of our interns is working on trying to do this."

(And, while you're visiting the Botanical Conservatory, be sure to see the succulents and other desert plants including the Madagascan spine forest plants that lemurs climb on; the giant leaves of the Titan arum plant; and the Mimosa pudica aka sensitive plant. "Its leaves fold up when touched,” Sandoval says.)

Meanwhile back to the midges. The chocolate midges.

Have we thanked them enough yet?

Thank you, midges.

The National Park Service describes the chocolate midges as "very small flies with long, complicated names: Ceratopogonidae, various species of Forcipomyia and Euprojoannisia. No bigger than the size of pinheads, midges seem to be the only creatures that can work their way into the intricate flowers to pollinate. They are most active in their pollination duties at dusk and dawn, in sync with the cacao flowers, which fully open right before sunrise. Without the midges, there would be no chocolate!"

"Today cacao trees are often is cultivated in open plantations, rather than in the humid shade of their natural rainforest habitat. Plantation cacao produces many flowers, but on average, only three out of 1000 flowers become pollinated and produce seed pods. From a midge's point of view, plantation cacao does not equal natural rainforest cacao!"'

And quite appropriately, Theobroma cacoa (named by Swedish botanist Carl Linnaeus in the 18th century)  means "food of the Gods."

Really, it's amazing that these tiny flies can pollinate the flowers at all. Ask an Entomologist says that "Oh, and the flies are bad at flying. Oh, and they can barely carry enough pollen to pollinate one flower. Oh, and each flower only typically lasts between 24-48 hours."

Only one out of every 400–500 flowers produce fruit, according to Ask an Entomologist. The plant "can produce upwards 50,000-100,000 flowers in it's 25-year lifespan. On average, a tree can produce 100-250 fruiting pods over its life....Only 10-30% of the pods will make it to maturity. Each of the pods produces between 20-50 beans which are covered by a sweet flesh that is edible. Approximately 400 beans are required to make one pound of chocolate."

"So let's max this all out and say you have a tree that produces all 250 pods in its life, 30% of the pods make it to maturity and all those pods produce 50 beans. That's 3,750 beans over its 25-year lifetime, which means one tree can make about a whole whopping 9 lbs. of chocolate."

Even more reason to express our appreciation.

Thank you, midges!

Emily Dorrance, former student project manager of the BOG, and now a BOG volunteer, peers from a patch of lupine.

Not so with the Biological Orchard and Gardens (BOG) on the University of California, Davis, campus. It's a 24,000-square foot treasure, a living museum planted not only with several dozen species of heritage fruit trees, but landscaped with colorful mini-gardens.

This spring scores of wildflowers bloomed in awe-stopping glory, prompting passersby to pull out their cell phones and take selfies. 

“The project began in 2010 when a group of students raised the money to convert an under-utilized lawn into a working orchard with fruits free for everyone to enjoy,” related former student project manager and now BOG volunteer Emily Dorrance. She recently graduated with a bachelor of science degree in environmental policy analysis and planning.

“Since then, the team has grown to involve many other UC Davis faculty, staff, and student groups," Dorrance said. ”Ernesto Sandoval, manager and curator of the UC Davis Botanical Conservatory, has been an advisor to the BOG student leadership for many years now and continues to be an important partner!”

At its core, BOG is a collaboration of students, staff and academic programs and an outdoor ecological laboratory that directly supports the university's popular Introduction to Biology course. Or, as the BOG Facebook page indicates: "An agro-biodiverse collaboration between students, staff, academic specialists and programs at UC Davis!"

BOG is located in front (or back) of the Mann Laboratory on Kleiber Hall Drive, depending on which way you're going! If you park in Lot 26, off Kleiber Hall Drive, it's a short walk down the sidewalk to BOG.

"The orchard you see today was planted two years ago," Dorrance noted. "The wildflowers were seeded four years ago and continue to self-seed, with some supplementation.We're planning on planting some more permanent plantings in the fall. The Mediterranean plots surrounding the orchard will have some more seasonal variety as well! I don't think we have any major planting plans for this summer but that could change!"

Among the flowers blooming in the Bog in the early spring, by color:

• Red: European red flax, Linum grandiflorum rubrum, an annual that's native to Algeria
• Yellow: tidy tips, Layia platyglossa, an annual that's native to California
  --The seep monkey flower, Mimulus guttatus, native to California
  --Lupine, Lupinus, native to North America.
• Blue: Desert bell, Phacelia campanularia,  an annual herb that is native to California and  endemic (limited) to California.
• Lavender: Phacelia, also called Lacy phacelia, blue tansy or purple tansy (Phacelia tanacetifolia), native to the southwestern United States
  --Lupine: Lupinus, native to North America
• Red-Orange-Yellow: Blanket flower or Gaillardia (Gaillardia × grandiflora), native to North and South America
• Orange: California golden poppies, Eschscholtzia californica

The orchard contains heritage fruit tree varieties threatened with commercial extinction. They include the Gravenstein and Johnathan apples; the Suncrest peach; the Bleinheim apricot, the Mariposa plum and the Meyer lemon. See the full list of trees as well as some fun facts here: https://thebogatucd.wixsite.com/bogucd/single-post/2017/07/18/BOG-Fruit-Trees.

In 2013 BOG received a "Go Green" grant from the UC Davis Dining Services. Then last month, the Green Initiative Fund (TGIF)  awarded $19,934 to the BOG for final site development. It was a major effort.  (On its Facebook page, BOG thanks Kelly Richmond and Andra George for help on the grant and supporters Geoffrey Benn, Ivana Li, Pat Randolph, Lee Anne Richmond, and Peter Hartsough.)

Future plans? According to the website: "The BOG is joining the campuswide effort in transitioning towards a landscaping genre that embraces lawn reduction and plantings more suitable for the teaching, outreach and research mission of the university and sustainability practices. The motivation for the BOG is to serve as a teaching garden for multiple university courses and provide a relaxing space to enjoy the outdoors and simply delicious fruit. The BOG's main function is to serve a demonstration of and test site for plants more suitable to the region's hot dry summers and cool wet winters, with a focus on drought tolerant plants less commonly available in the Sacramento Valley."

When we stopped by the BOG in mid-April, the Phacelia tanacetifolia proved to be a favorite: honey bees (Apis mellifera), male and female Valley carpenter bees (Xylocopa varipuncta) and yellow-faced bumble bee (Bombus vosnesenskii) were all over it. It's fairly uncommon to see male Valley carpenter bees--"teddy bear bees" or green-eyed blonds--foraging, but there they were, along with the female of the species. "The girls" are solid black in a clear-cut case of sexual diphormism.

Want to get involved? The BOG seeks volunteers, interns and donors. See its website at https://thebogatucd.wixsite.com/bogucd or its Facebook page at www.facebook.com/ucdBOG  or email "thebogatucd@gmail.com."

You can even adopt a tree!

Or become buddies with a bee!

(Note: Most of the annual wildflowers have "passed" since our visit in mid-April, but the orchard is thriving with newly formed fruit.)

They danced in it, rolled in it, and bathed in it.

The honey bees just couldn't get enough of the rock purslane (Calandrinia grandiflora). 

Last week when we visited Vacaville's El Rancho Nursery and Landscaping. nursery, owned by Ray and Maria Lopez,  it was like a free-for-all at the French Laundry. The bees clustered around the rock purslane flowers, waiting inpatiently for them to open. No sign read  "Closed" but some of the magenta flowers had not yet unfolded.  No matter. A robost honey bee tried to slip inside. What do you mean, I'm too big?

Nearby, two other bees, sisters in honeyhood, shared the same flower as another honey bee tumbled happily out of her flower and made a beeline for the next one.  

Ernesto Sandoval, curator of the College of Biological Sciences Greenhouses at UC Davis and Robbin Thorp, emeritus professor of entomology at UC Davis, say that bees love Calandrinia grandiflora. The plant, native to Chile, blooms here in late summer and early fall. 

"It has has bright red-orange pollen that honey bees love," Thorp said.

They do, indeed.