I just wanted a photo of a mud dauber nest…

You know the old saying: “You can never find a mud dauber when you need one.” Of course you do. Well, the old adage proved itself yet again last week when I went searching for mud dauber wasp nests to photograph.

I came across this black-and-yellow mud dauber (Sceliphron caementarium) at a small riverine wetland at The Nature Conservancy’s Niobrara Valley Preserve last summer.

I’m writing a magazine article on wasps and wanted some photos of various wasp nests to help illustrate it. We have an old garage with lots of great places for mud daubers to build their mud nests, but a thorough search found only a couple empty remnants of very old nests. That’s ok, I had a backup plan.

The Derr House, the field headquarters for our Platte River Prairies, has always been a dependable spot to find nests. Those nests make great discussion subjects with guests. In fact, I’ve told the same story many times:

“Mud daubers are fascinating little creatures. First of all, they don’t attack people, so you don’t have to worry about them. More importantly, a female mud dauber builds a little mud tube on the sides of buildings and other structures. Then, she hunts down and paralyzes some spiders and jams them into the tube. The wasp lays an egg in with the spiders and seals up the hole with mud. The larva can feed on the spiders until it pupates and emerges as an adult.”

Sure enough, when I stopped by the Derr House, I was able to find plenty of mud nests up near the eaves. A couple were extra big, so I figured I’d start by photographing them. They were up high, so I backed my pickup close and set up my tripod on the tailgate. Perfect. Except there was something weird about the mud nest; it had little brown circles all over it. That didn’t seem right.

The mud nest with little brown circles.

Well, I was already set up on the tailgate, so I went ahead and photographed the nest, weird circles and all. While I was there, though, I also got curious and decided to investigate a little more. By a strange coincidence, I happened have a couple razor blades in the truck and decided to use one to cut away some mud. It was surprisingly difficult, even with a brand new blade, but I did eventually manage to open the nest a little. What I found was definitely not in line with my story about paralyzed spiders in a mud tube. These tubes appeared to be filled with lots of little leaves.

Tiny leaf sections were stuck together and seemed to be lining the long holes inside the nest.

Well, now I had to keep going and figure what what was inside the leaves, didn’t I? I had a suspicion, but wanted to get photos so I’d be able to confirm or deny my hypothesis. I carved out a part of the mud nest that contained a couple of the leafy cylinders and laid down on the bed of my truck with the cylinders and my camera. I painstakingly peeled the leaves apart on one cylinder… Ok, I tried to, but ended up making a pretty good mess of it. I did eventually manage to figure out that there were multiple hollow sections to the cylinder, each wrapped up tightly in leaves.

Something is peeking out at me from inside this leafy cell.

Even with the razor blade (somewhat dulled by cutting through hardened mud, of course) it was difficult to slice into those cells to see what was inside. I managed to mangle a couple before finally making a hole big enough to expose a pale larva with little orange spikes on it. Over the next few minutes, I photographed it and a couple of its siblings as they crawled around my tailgate.

After photographing the larvae for a while, I noticed one of the leafy cells had an odd texture on one end of it (below). I photographed it, figuring I could try to decipher it later. I’m glad I did because it became a helpful clue.

Odd texture on the end of one of the cells.

As I looked at the remains of the section of mud nest I’d carved off the wall, I noticed something brown had been exposed when the mud cracked. I peeled the mud apart further and finally found what I’d initially set out to photograph – an actual mud dauber pupa. So, this was, in fact, a mud dauber nest. It’s just that it seemed to have a lot of non-mud-daubers in it too. Have you already guessed what they are?

A mud dauber (I’m pretty sure!) in its pupa. Though the glare from my flash makes it a little difficult, but I think I can make out the head on the right and the yellow legs against a black body further to the left.

When I got home, I quickly worked up the photos and sent a selection of them to Heather Holm, who (among many other things) knows more about wasps than anyone I know. You might remember the post I wrote a year ago, in which I rhapsodized about her fantastic book on the topic. I asked her to help me interpret what I’d seen, and specifically, if leaf-cutter bees (Megachile sp.) were known to share a nest with mud daubers.

Sure enough, Heather graciously confirmed what I’d guessed. Apparently, at least some leaf cutter bees are known to reuse the holes in mud dauber nests. Heather also agreed that the odd texture I’d seen on one cell was the remains of pollen and a lot of fecal pellets (poop). Wasps don’t provision their nest cells with pollen, so that pretty well confirmed the bee hypothesis.

What’s interesting to me is that it appears that both black-and-yellow mud daubers and leaf cutter bees were using the same structure at the same time. Did the bees move in after the previous year’s wasps had exited their holes? If so, was the wasp pupa an old one that didn’t emerge? That seems unlikely. Surely it would have decomposed by now if it had died, right? Did a black-and-yellow mud dauber reuse a hole from that nest too? Or is the pupa I found actually a blue mud dauber (Chalybion), which is also known to reuse the holes of black-and-yellow mud dauber nests?

The next time I get out to the Derr House, I think I’ll grab a little more of that nest and put it in a jar. Hopefully, I’ll get to see who emerges from all those holes and flesh out this story a little more. I’ll let you know if that works. In the meantime, I need to get this magazine article written…

Photos of the Week – April 1, 2022

One of the most gratifying parts of my career has been the opportunity to design and carry out restoration work – especially taking cropfields, adding wetlands to them, and then planting them with diverse seed mixes. It’s really hard to encapsulate the joy, energy and pride that comes from that work.

I could make squiggly lines across a site with flags and big equipment would come in and turn those into wetland sloughs. I could walk around with buckets strapped to my waist and grab seeds from plants and at least some of those seeds would germinate and establish diverse plant communities. Most importantly, I could then spot the same bees, grasshoppers, small mammals, ants, and birds in those restored sites as could see in the adjacent unplowed prairies, helping me feel like I’d accomplished the primary goal: stitching fragmented grasslands back together.

Hubbard Fellow Emma Greenlee plants prairie with a ‘drop spreader’ that literally drops the seed right on the ground.
Our other Hubbard Fellow, Brandon Cobb, drops more seed on the ground. He’s using a more specialized upland mix on some of the spoil piles created during wetland creation. He’s demonstrating a ‘straight downward toss’ technique because the wind was howling as he did the work.

Since I’ve moved out of the role of land steward for the Platte River Prairies, I’ve gotten to watch and help other people experience those same emotions. This time around, it’s Cody Miller, our Preserve Manager, who is directing the latest restoration project. My jobs are to give ‘old man advice’, when asked, and to cheer everyone on from the sidelines. …And to take photos, which is why today’s post is another one (two in a week!!) full of people photos, instead of insects, flowers, or other small things. Don’t worry, I’ve got a couple of old standards coming soon.

A mixture of seed from both the mesic and wetland mix floated to the edge of a small pool of water in one of the wetlands.
Here’s a view of the drop spreader as Emma went past. Below is a video of the machine in action. It’s very exciting. It drives both up AND back across the field!
Cody (left) and Booker Moritz fill barrels with seed to load into the spreader when Emma gets back to the edge of the field.
Here is the hand-harvested seed that got mixed in with machine-harvested grass seed and put into the spreader. The total mix for the site had 153 plant species represented.
You can see that the seed mix is plenty messy. We run it through hammermills to break the seed apart but don’t worry about removing inert matter. The drop spreader handles quite a bit of junk, which saves us time on seed processing.
Here is Cody’s wetland design, which closely followed old river channel scars (the whole Platte valley is alluvial soil laid down by the river many years ago). Groundwater is not far below the surface at this site, so those shallow sloughs will turn into sedge meadow habitat with some exposed open water during high groundwater periods. Below is a fly-by of the same wetlands.
Cody and Emma talk about the restoration process as they plant.

This 50 acre site will be very weedy for a few years, but by year 3, 4, or 5 it should be dominated by the plants we harvested and seeded. Once everything is established, Cody will start using fire and grazing to manage for habitat structure and help encourage as many animals as possible to colonize the restoration from adjacent prairies. He’ll also get to experience the wonder of walking around a site he turned from bare ground into prairie and wetlands. I can’t wait to watch him do it.

Many thanks to the U.S. Fish and Wildlife Service, Ducks Unlimited, and Nebraska Game and Parks for helping to fund this project.