Photo of the Week – May 26, 2017

Shell leaf penstemon (Penstemon grandiflorus) is one of the showier wildflowers in the Platte River Prairies during late May and early June.  It is most often found in dry soils and where the surrounding plants aren’t overly competitive.  We often see populations increase after droughts and grazing events and then decrease again as grasses recover their vigor in subsequent years.

Shell leaf penstemon has big showy flowers that are just the right size for bumblebees, but are used by other pollinators as well.

For years now, I’ve been periodically coming across patches of shell leaf penstemon plants that have been decapitated by a rabbit or something.  That wouldn’t be surprising except that the top of the plant is usually just lying next to the plant uneaten!  There is a single angular slice in the flowering stem, usually well below the bottom-most flower, and the entire flowering stem just (apparently) falls to the side.  I’m at a loss to explain this.  I don’t know if an animal is doing this to lick the juices out of the stem for some reason?  I honestly can’t think of any other good reason for what I’m finding – not that juice licking is a very good reason…  I’d love to hear from someone who knows the answer to this.

Yesterday, Nelson (our land manager) and I were touring a colleague from Wisconsin around one of our prairies and found a patch of decapitated penstemon.  As we were discussing the mystery, Nelson grabbed one of the stems and saw what he thought might be a black stem-boring insect.  As we peeled apart the stem to see it, it turned out to be a small black wasp or bee that Nelson had apparently squished when he picked up the stem.  Before I could get a very good look, the wind blew the deceased insect off the stem and down into the grass at our feet.  I didn’t worry too much about it, but as we continued to peel open the stem, I wished I’d tried to recover the insect.

Here is the detached flowering stem Nelson picked up.

The penstemon stem was stuffed full of flies.  Flies of all shapes and colors.  There were more than 20 of them, separated intermittently by wads of dried plant material.  Based on what we found, I guessed the insect we saw, and then lost, must have been a wasp and that it was laying eggs in the stem and provisioning them with flies.  I took the stem home to photograph it and then sent the photos to my friend Mike Arduser, who knows everything about bees, and an awful lot about wasps and other insects as well.

Here is a close-up photo showing the diversity and abundance of the flies jammed into the stem. I looked, but didn’t see the eggs that must have been there.

Mike said the insect was very likely a wasp in the genus Ectemnius that usually uses flies as the food source for its larvae.  They frequently excavate the pith out of twigs and other stems.  Based on the behavior of other wasps, I assume the flies were paralyzed, not dead, and that there was an egg laid with them, but I didn’t actually see any eggs.  According to Mike, Ectemnius wasps have a kind of “cuboidal” shaped head and the various species are between 6 and 14 mm in size.

I’m very certain the wasp wasn’t responsible for cutting the flowering stem off the penstemon, but it was pretty interesting to see something taking advantage of the destruction.  I didn’t see any other stems with similar nests in them, but I’ll sure keep an eye out for that in the future…

Now if I can just figure out who or what is decapitating our penstemon plants, I’ll be satisfied.  Until the next mystery comes along.


On the whole, you did pretty well on the plant game this week.  I tricked most of you on the first one, but the majority of you guessed correctly on the second and third questions.

On the first question, 161 people voted (as of this afternoon) and almost 50% chose Candy Lovegrass as the fake name, which is wrong – it’s a real plant.  Look it up if you like.  The actual fake name in that list was Clark’s Blisterpod, which came in 3rd at 22%.

More people (212) were bold enough to guess on the second question, and 50% of you were correct that Bully Pulpit was the fake plant.  However, about 1/3 of you guessed Beefsteak Plant, which sounds fake but is real – and invasive in at least some places/situations.

On the third question, 172 people voted, and 47% correctly identified Slipper Cherba as a fake plant name.  Autumnal Water Starwort and Beaked Ditchgrass were second and third in the voting with 25% and 21%, respectively.  I really thought more people would go for Beaked Ditchgrass, but what do I know?

Thanks for playing my goofy game.  The hardest part of putting it together is coming up with names that are weirder than the real ones…

Photo of the Week – April 11, 2013

Sometimes, you can see a lot by just sitting down.

I carved out some time in the field last Friday to collect data on poison hemlock in our research plots.  After finishing that, I had about half an hour before I needed to head back to the office, so I took my camera for a walk along the creek running through our Platte River Prairies.  Not having a particular agenda, I stopped to look at a tree that had been recently felled by beavers.

This tree, cut down by our local beavers, had sap seeping from the stump last week.  The Nature Conservancy's Platte River Prairies, Nebraska.

This tree, cut down by our local beavers, had sap seeping from the stump last week. The Nature Conservancy’s Platte River Prairies, Nebraska.

As I was admiring the patterns of tooth marks on the stump, I noticed an interesting-looking little fly hanging around.  As I watched, the fly started to feed on the sap that was oozing out of the tree.  Taking advantage of the fact that the fly was distracted by its meal, I managed to get a couple photos of it.

This fly seemed to be enjoying its meal enough that it didn't mind me sticking my lens in its face.

This fly seemed to be enjoying its meal enough that it didn’t mind me sticking my lens in its face.

Since I had time, I decided to sit and watch the fly for a bit.  Before long, another – different – fly came along.

A second fly joins the meal.

A second fly joins the meal.

One of my favorite statistics is that there are more than 37,000 species of flies in North America.  That seems an almost unfathomable diversity.  Taking that into account, I guess I shouldn’t have been surprised to see a third kind of fly arrive at the stump…

Fly #3.  A big green one.

Fly #3. A big one with blue and green stripes on its abdomen.


A rear view of fly #3, showing the striped abdomen.

A rear view of fly #3, showing the striped abdomen.


A tiny wasp (2mm long).

A tiny chalcidoid wasp was on the stump as well, though not feeding on sap (thanks to Mike Arduser for identifying it for me – Mike says they are a group of parasitic and important wasps).  The quality of this image isn’t very good – my excuse is that the wasp was BARELY 2mm LONG and I had to crop it quite a bit so you could even see it…


A tiny red mite came ambling along...

A tiny red mite came ambling along too…  It was about the same size as the little chalcidoid wasp


Fly #3 didn't like Fly #1 working over the same puddle of sap and lunged at it

Fly #3 apparently didn’t like Fly #1 working over the same puddle of sap.  This photo captures Fly #1 rearing back as Fly #3 lunged at it.

I wish I’d had more time to stick around; it would have been fun to catalog all the little critters that visited – or were living in – that beaver stump.  I also wish I would have gotten a shot of the little wolf spider hiding in the pile of wood chips at the base of the stump – it darted out and almost caught one of the flies when it landed nearby, but didn’t stick around for a photo.  Too fast for me…

I think my short time watching the beaver stump brings up a number of interesting points that I could focus on as the overall theme of this blog post.  I could focus on the odd side benefits provided by the work beavers do.  I could focus on the crazy diversity of life found on a single tree stump.  I could focus on the way creatures of all different kinds are able to take advantage of unexpected resources (like oozing tree sap) when they appear.

But I think the biggest point is this:  You can see and learn an awful lot by just sitting down and watching.