Downy Skullcap and the Amorous Skippers

Apparently I planted some Downy Skullcap (Scutellaria incana) in our garden last year and then promptly forgot, so it was a delightful surprise when the vivid blue flowers began to bloom in long stalks above gray-green foliage.

Downy Skullcap (Scutellaria incana) with Flower (Syrphid) Fly

Downy Skullcap (Scutellaria incana) with Flower (Syrphid) Fly

Each long tubular flower has an entrance with a hood- or cap-like overhang at the top, and a floor with a white pathway beckoning to visitors who might help pollinate the flowers.

Downy Skullcap (Scutellaria incana) Flower

Downy Skullcap (Scutellaria incana) Flower

The almost sapphire blue flowers are especially attractive to bees, and are thought to be most often pollinated by Bumble Bees (Bombus species) but they entice other pollinators as well, including flower flies, bee flies, and small butterflies.

I watched for visitors to the flowers in our garden and at another near-by site, Bowman’s Hill Wildflower Preserve. At both locations, bees were the most frequent visitors on days when I checked, and of the bees, Small Carpenter Bees (Ceratina species) were the most common.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

Don’t be put off by the fact that they are called carpenter bees.  These tiny bees won’t be drilling holes in the deck, siding or wood trim of your home.  They nest in the stems of dead or broken twigs, excavating nesting cells by chewing through the pith, the softer tissue inside the stem.  Small Carpenter Bees are pollinators of many plants, especially those with small flowers.

Each bee crawled inside the flower, disappearing down the throat until they reached the nectar reward at the bottom.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) crawling down the throat of the flower to reach the nectar reward

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) crawling down the throat of the flower to reach the nectar reward

But it wasn’t just nectar they were after.  Bees need a balanced diet.  They wanted pollen, too, for the protein and lipids it provides.  The flowers’ reproductive parts, the stamens and pistils, are hidden under the hood at their entrance.  After emerging from drinking nectar at the depths of a flower, each bee then checked under the hood for pollen, which is dispersed from the anthers at the stamens’ tips.  Some bees even went straight for the pollen without bothering with the nectar.  Hopefully some of that pollen was later deposited on the stigma of another flower, the female flower part where pollen must be placed in order for pollination to occur.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) emerging from the flower

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) emerging from the flower

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) harvesting pollen

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) harvesting pollen

Much larger relatives of these tiny bees, Eastern Carpenter Bees (Xylocopa virginica), also visited the flowers.  Although these bees can be excellent pollinators, it pains me to tell you that in the case of Downy Skullcap, Eastern Carpenter Bees are thieves. They can’t access the flowers’ nectar by going through the inviting entrance, thus interacting with the flowers’ reproductive parts and helping with pollination.  So instead, they bite through the floral tube near its base, directly accessing the nectar, doing nothing in return to assist the plant in its reproductive goals.  Interestingly, a Honey Bee tried to discourage the Eastern Carpenter Bees from this dishonest activity by trying to chase them away, with some success. And yes, regrettably, Eastern Carpenter Bees might choose to nest in the wood of your home.

Downy Skullcap (Scutellaria incana) with Eastern Carpenter Bees (Xylocopa virginica) robbing the flower of nectar by biting through the floral tube to drink it.

Downy Skullcap (Scutellaria incana) with Eastern Carpenter Bees (Xylocopa virginica) robbing the flower of nectar by biting through the floral tube to drink it.

While looking for Downy Skullcap flower visitors in our garden, I spotted a male Zabulon Skipper drinking nectar.

Male Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower

Male Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower

A moment later, I noticed a female Zabulon Skipper, doing the same.

Female Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower. Notice the bee disappearing into the flower above hers.

Female Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower. Notice the bee disappearing into the flower above hers.

Then the male flew over to the female and suggested a ‘hook up’.

Female (top) and male (bottom) Zabulon Skippers, negotiating a hook up. Their wings are a little out of focus because both were vibrating them energetically as a lead up to an agreement.

Female (top) and male (bottom) Zabulon Skippers, negotiating a hook up. Their wings are a little out of focus because both were vibrating them energetically as a lead-up to an agreement.

She was apparently persuaded by his pitch.  They went off to a more secluded spot, and stayed there beyond the limits of my attention span.

Zabulon Skippers, mating

Zabulon Skippers, mating

Zabulon Skippers, mating

Zabulon Skippers, mating

These small butterflies are common in gardens and natural areas, specializing on many grass species as food for their caterpillars, including Purpletop (Tridens flavus), Purple Love Grass (Eragrostis spectabilis), and other related species.

Purpletop (Tridens flavus), a caterpillar food for Zabulon Skippers

Purpletop (Tridens flavus), a caterpillar food for Zabulon Skippers

When the flowers have finished blooming and drop away, a cap-shaped calyx, the set of sepals that act as bud scales remains, providing the inspiration for the common name ‘skullcap’.

Cap or dish like calyxes of Downy Skullcap (Scutellaria incana)

Cap- or dish-like calyxes of Downy Skullcap (Scutellaria incana)

‘Downy’ in the common name and ‘incana’ in the scientific name, which means hoary or quite gray, refer to the short soft hairs present on the flowers and stems of this plant. Hoary Skullcap is another common name for the species.

Downy Skullcap is native in the United States from New York west to Wisconsin, south as far as Texas and the Florida panhandle.  It can tolerate full sun to full shade, dry to moist soil. Blooming in mid-summer, it makes a dramatic addition to a garden.  Add it to yours and wait for the real drama (food foraging, bee face-offs, theft, flirtation, sex!) to begin.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

Resources

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Eaton, Eric R.; Kauffman, Ken.  Kaufman Field Guide to Insects of North America.  2007.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

Willmer, Pat.  Pollination and Floral Ecology. 2011

Wilson, Joseph S.; Carril, Olivia Messinger.  The Bees in Your Backyard. 2016.

Illinois Wildflowers

Lady Bird Johnson Wildflower Center Plant Database

Missouri Botanical Garden Plant Finder

USDA NRCS Plants Database

 

24 thoughts on “Downy Skullcap and the Amorous Skippers

  1. Hi M,

    What a delightful surprise! This year for me it was a wild pansy. It took two years to surface! I think of you everyday as I marvel at the new bugs (mostly bees) at our house. Since we are Covid bound, we have our own backyard movie theater and much of the credit goes to you and your colleagues at the Wildflower center. P

  2. What a great read. Skullcap will be an addition to my garden. Thank you, thank you for the enjoyable posts, Mary Anne!

  3. Always a treat to receive notification of your posts. As always, great photos and informative interesting narrative! Appreciate your efforts.

  4. Wonderful post and the photos are amazing, Mary Anne! I’m inspired – so I’m heading out to the garden now to visit my skullcap.

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