Large Leopard Slug (Limax maximus) against brick wall.

A Tale of Villainous Carpenter Bees and Helpful Slugs

Today’s Nature Journal Summary

DateMay 16, 2022
TimeAround 6:30am
Habitat ExploredSuburban neighborhood, second- and third-growth woodland with mixed pine and hardwood trees.
WeatherPartly sunny. Sky was lightening up but still dark under the trees. Cool breeze blowing but air feels humid.
Temperature (Fahrenheit / Celsius)70ยฐF / 21ยฐC
Wind13 mph from 220ยฐ SW to NE
Humidity84%
Animals EncounteredCarpenter Bees (Xylocopa virginica) – Signs of their presence only.

Leopard Slugs, aka Giant Garden Slugs (Limax maximus)

American Robin (Turdus migratorius)
What I SawTidy pile of fresh, fine sawdust directly under my porch railing. Evidence of a female Carpenter Bee chewing her way into the wood to make a nest in which to lay her eggs.

Lots of Leopard Slugs. Big ones as long and thick as my index finger were down around my foundation, some vertical on the brick and the lower section of siding. Much smaller ones were on my porch steps and railing.

Evidence of slugs or snailing feeding on the algae growing on the side of my house continually shaded by trees. Circuitous, overlapping routes, but no sign of the feeders on the house.

Early morning American Robin hopping along the grass, already pulling its breakfast from the soil.
What I HeardLots of twittering birds waking up for the morning. Especially loud in the pines.
ThoughtsReally, REALLY annoyed at the damage to my porch railing by the Carpenter Bees.

Like the quiet peace of the early morning. No one else is around. Don’t even see any lights on in my neighbors’ homes. Have the area to myself, except for the creatures.

The biggest Leopard Slugs are pretty disgusting to watch. They move a lot faster than I expected and leave a lot of slime. I can see their breathing pores and the small remnants of their shells under their skin. The smaller ones seemed less gross. But none of them are hurting me in any way, so live and let live.
05/16/2022 Now I Wonder Nature Journal Summary

I love nature. Obviously. Why start a nature journal if I didn’t love it? And yet….

I don’t love all nature equally. Especially the “nature” that attacks my house.

Let me explain.

I step outside into a warm, clear morning. It’s around 6:00am and all is quiet. Dawn has just barely broken. Soft beams of sunlight filter through the sweet gum leaves. Early birds twitter and sing in the pines. And I start my early morning search for interesting creatures.

I start forward onto my porch but stop short, distracted by a pale patch of color near the edge where nothing pale should be. I lean closer to peer at the patch. What am I looking at?

Suddenly, my brain translates the message my eyes sent and I am aghast. The pale patch is a pile of fresh, powdery sawdust!

Now, I wonder where that came from?

I crouch down and run my fingers slowly along the bottom edge of the porch railing, above the sawdust pile. My fingers find a precise round hole in the wood, slightly larger in diameter than a milkshake straw. Perhaps there’s a teeny, tiny madman with a power drill running around my neighborhood? Nope.

This is the work of a female Carpenter Bee (Xylocopa virginica).

A pile of sawdust chewed out from underneath a porch railing by a female Carpenter Bee building a nest, with a key for scale.
This pile of fresh sawdust was hewn from the underside of my front porch railing The sight made an unpleasant surprise one early spring morning Photograph taken by the author Copyright Now I Wonder

The Villain: Carpenter Bees (Xylocopa virginica)

The Wood Chewers

Found throughout the eastern United States, female Carpenter Bees chew their way into wood to make long, narrow tunnels. The tunnels are extensive, extending up to 12 inches long. Once the tunnel reaches a suitable length, they crawl back towards the entrance, laying a single egg at a time. They wall each individual egg up before laying the next, essentially filling the tunnel in with eggs, each housed in its own cell.

And they have absolutely riddled my porch railings with their tunnels.

Carpenter Bee (Xylocopa virginica) on a Passionflower (Passiflora incarnata).
The guilty party acting innocent Photograph taken by the author Copyright Now I Wonder

Female Carpenter Bees are perfectly adapted to this task. Their mandibles are strong and sharp, allowing these bees to gnaw their way into the hardest wood.

Unfortunately for me, the Carpenter Bees in my neighborhood don’t need to work that hard. Why should they expend effort to chew into hardwood trees like oak or maple when my beautiful porch railing is made of soft, buttery pine? Pine is a soft wood and thus child’s play for a determined female Carpenter Bee to mine. Natural selection rewards creatures that can reproduce quickly and efficiently and my porch railing is apparently the best nursery site in town.

I am outraged.

Damage to underside of porch railing by female Carpenter Bee (Xylocopa virginica).
This photograph of the underside of my front porch railing shows the impossibly neat round hole chewed into the wood by a female Eastern Carpenter Bee <em>Xylocopus virginica<em> intent on creating a protected space for her eggs Photograph taken by the author Copyright Now I Wonder

But there’s no saving my porch railing now. I might as well let nature take its course and do my part to support the next generation of this important pollinator species. I stand, cast one more disgusted glance at the pile of sawdust, and face the yard.

I’m hunting creatures and I want to see one that will remind me that nature is pretty cool.

Then I spot the Leopard Slug.

The Helpers: Leopard Slugs (Limax maximus)

A large Leopard Slug (Limax maximus), glistening with slime, nearly 4 inches (10 cm) long, and as thick as my finger, glides slowly along the brick of my foundation.

Why be so pleased? Those familiar with slugs might put them in the same category as female Carpenter Bees – that is to say, the “creatures that destroy my property” category.

Voracious herbivores, slugs emerge at night to feed on plants. Like their snail cousins, slugs are notorious for destroying plants, especially the soft, tender garden plants that humans cultivate.

Leopard Slug (Limax maximus) with key for scale.
A Leopard Slug Limax maximus with a key for scale This gastropod was heading for deep leaf litter to hide itself away from the heat of the sun and daytime predators Photograph taken by the author Copyright Now I Wonder

However, I’m not a gardener.

I love nature and enjoy identifying plants. I appreciate the fundamental and irreplaceable role plants play in every ecosystem. I am endlessly grateful for the farmers who grow my food and battle the damage these creatures cause every day.

I don’t have a garden. But I do have algae.

The Algae Eaters

The north side of my house never receives direct sunlight and is surrounded by trees. The trees release huge amounts of water every day as they photosynthesize. Combined, these factors result in an dim and extremely humid micro-climate perfect for the growth of algae.

A thin film of algae tinges the north side of my house green. Every morning, I see tangible evidence that these slugs do at least some good for this particular human.

During the day, slugs hunker beneath leaf litter to protect themselves from drying out. At night, they emerge to feed. Those that hide at the base of my foundation climb straight up and find a bonanza – a verdant pasture of algae. They munch happily throughout the night, rasping the algae away with their hundreds of tiny teeth, and leaving trails of clean paint in their wake.

Feeding slugs leave circuitous tracks through algae.
Photograph taken by the author Copyright Now I Wonder

Final Thoughts

Nature is never good or bad, only balanced. I’ve learned this lesson today without moving more than a few feet from my front door.

Yes, Carpenter Bees chew expensive porch railings into sawdust and yes, Leopard Slugs chew garden plants into oblivion. On the other hand, Carpenter Bees help pollinate many plants upon which humans rely, and Leopard Slugs (at least my Leopard Slugs) help control the algae which grows on my house between power washings. And so, I must take the bad with the good.

But on a practical level, I sure do wish the Carpenter Bees would find something besides my house to chew on and that my Leopard Slugs would feed in straight lines.

Where to go from here

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Christine
Christine is the creator and author of NowIWonder.com, a website dedicated to the animals and plants that share our world, and the science that helps us understand them. Inspired by lifelong exploration and learning, Christine loves to share her knowledge with others who want to connect with wild faces and wild spaces.

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