September 10, 2022

Kelly Dix and Glenn Marangelo looking at insects on the sunflowers.
Kelly Dix and Glenn Marangelo looking at insects on the sunflowers.

From a distance, this sparse patch of sunflowers looks nondescript. You’d have no idea that it’s the stage for a gripping insect drama. But here we are, five adults, completely engrossed in this miniature world in front of our eyes. We’ve already spotted a golden paper wasp, two magnificently hairy velvet ants, and a spined assassin bug. And we keep spotting more creatures, each of them exciting. It’s a scramble to keep track of them all and get photos.

The Rock Creek Confluence property.
The Rock Creek Confluence property.

We’re about 18 miles southeast of Missoula today, close to where Rock Creek flows into the Clark Fork River. We’re standing in a rocky wetland area on the Rock Creek Confluence property, a Five Valleys Land Trust site that offers public day use and an interpretive trail. Prior to 2016, this wetland was a pond, kept full with irrigation water. Since then, Five Valleys Land Trust has returned their water right to in-stream flow, supporting bull trout, cutthroat trout, and other inhabitants of Rock Creek. And the once-full pond has become a shallow wetland under restoration. Now the water levels fluctuate with the groundwater. Volunteers have helped plant a variety of native plants, and others are establishing on their own. A deer fence currently surrounds the area, limiting attention from deer while the plants develop.

Getting started with the insects

Golden paper wasp (Polistes aurifer).
Golden paper wasp (Polistes aurifer). (This photo is from another location.)

As part of the restoration project, we’re here today to document a few of the most visible insects we can find in this habitat. Glenn Marangelo of the Missoula Butterfly House is leading this field day. By the time I arrive (20 minutes late), there are three other naturalists helping with the search: Kelly Dix, Kristi DuBois, and Jenny Lundberg. 

We’re hovering excitedly around the sunflower patch, in the dry cobbles above the wetland. A golden paper wasp (Polistes aurifer) is still perching quietly on a sunflower stem. It’s exciting to see this native species here – at least in my observations around Helena, this wasp seems uncommon compared to the European paper wasp (Polistes dominula), a non-native relative that has become ubiquitous.

An assassin bug (Sinea sp.).
An assassin bug (Sinea sp.).

“Is that another assassin bug up above him, hanging from that flowerhead?” asks Jenny. 

There it is, an outlandish, long-legged tan bug with a narrow head and neck. 

“Really!? Oh, that’s cool!” says Glenn, every word full of excitement.

For all of their drab tan camouflage, assassin bugs (Sinea spp.) are vicious predators. They hunt any small or medium insects they can find, sucking the juices out of their hapless prey. And this is the second one we’ve seen here in these few minutes of looking. The other one dropped to the ground, where I was able to get photos of it.

Ambush bugs and velvet ants

An ambush bug (Phymata sp.) on the sunflower bracts.
An ambush bug (Phymata sp.) on the sunflower bracts.

We haven’t finished watching the assassin bug when I spot one of its more-colorful relatives trying to hide behind a flowerhead. This armored, rough-textured black and yellow creature is a jagged ambush bug (Phymata sp.). Remarkably camouflaged among yellow flowers, like goldenrods and sunflowers, these bugs prey on unwary flower visitors. But here, against the green bracts, this predator is obvious. It must realize how much it stands out, because soon it flies off, in search of a better hiding spot.

A velvet ant (family Mutillidae) crawling on the sunflowers.
A velvet ant (family Mutillidae) crawling on the sunflowers.

Just minutes before, we had spotted a velvet ant on the sunflowers. Wingless and antlike, but way fuzzier, we watched it crawl methodically along the plant, then drop to the ground when we disturbed it. Not ants at all, these unique wasps (family Mutillidae) are parasitoids that attack the young of certain other insects, especially ground-nesting bees and wasps. They seem rather uncommon, and it’s always a treat to see them. Don’t pick them up, though – some species can give a nasty sting when they’re attacked.

From forest to wetland

The ponderosa pine forest community.
The ponderosa pine forest community.

In the distance, we can hear the chipping of red crossbills from the mature ponderosa pine stand along the interpretive trail. A few minutes ago, the Clark’s nutcrackers were giving their nasal calls there, too. I arrived at the trailhead at the same time as Jenny. From there, it took us almost half an hour to walk the 1/3 mile from there to the wetland, distracted by the spiders, moths, and grasshoppers within the pine forest. From the invertebrates and the bird calls, it’s easy to tell: the community in the ponderosas is completely different from that of the wetland.

Here in the wetland, small flocks of migrating American pipits are landing to forage, giving their sharp “sip-it” calls. A killdeer is foraging in the mud. And right around us, we’re finding new insects so fast that Glenn is hard-pressed to both get photos and write everything down.

Webworm moths and ladybugs

A fall webworm moth (Hyphantria cunea) on a nearly-denuded chokecherry.
A fall webworm moth (Hyphantria cunea) on a nearly-denuded chokecherry.

The fall webworm moths (Hyphantria cunea) have completely denuded a small chokecherry, replacing the once-green leaves with a massive, silky web. We find one caterpillar still at home – the others have already moved on. The web also yields a couple of ladybugs. A convergent ladybug (Hippodamia convergens) has died here, though whether it was at the end of its life or got trapped into the webbing isn’t entirely clear. 

A nine-spot ladybug (Coccinella novemnotata). (This photo is from a different location.) Note the obvious black line where the two wing covers meet, an important field mark for this species.
A nine-spot ladybug (Coccinella novemnotata). (This photo is from a different location.) Note the obvious black line where the two wing covers meet, an important field mark for this species.

But near this ladybug we find one that’s still alive, a less-elongate creature with a conspicuous black line where the wing covers meet. It’s a nine-spot! This species (Coccinella novemnotata) is in decline – and even here in Montana, where people continue to spot them, they’re rather rare. When I found six of them in a sagebrush stand near Helena earlier this summer, they were vastly outnumbered by the 142 other ladybugs I counted. Nine-spots are always a special sight. After Kristi takes photos of it, we remove the nine-spot from the webbing. Before I can get any photos, it flies off.

White sagebrush (Artemisia ludoviciana) with honeybee visitors.
White sagebrush (Artemisia ludoviciana) with honeybee visitors.

We stop briefly by some clumps of white sagebrush (Artemisia ludoviciana) loaded with inconspicuous yellow flowers. Conspicuous or not, the honeybees have found them. Several dozen honeybees are getting lunch on these flowers, along with a couple of smaller flies.

Insects near the water’s edge

A striped meadowhawk (Sympetrum pallipes).
A striped meadowhawk (Sympetrum pallipes).

Out in the moister soil near the water’s edge, the striped ground crickets (Allonemobius fasciatus) are singing from their hiding places among the vegetation and the mud cracks. Meadowhawks (Sympetrum spp.), those red and black dragonflies, are in constant activity here, perching and making short flights. We spot at least five species: striped, black, band-winged, white-faced, and cherry-faced meadowhawks. A variety of lyre-tipped spreadwings (Lestes unguiculatus) are fluttering around us, too. 

A lyre-tipped spreadwing (Lestes unguiculatus).
A lyre-tipped spreadwing (Lestes unguiculatus).

Up close, the eyes of these damselflies are like blue ocean planets. With such prominent eyes, it’s no wonder damselflies and dragonflies are excellent hunters. It makes them hard to catch, too! I do manage to catch a striped meadowhawk (Sympetrum pallipes) for a closer look.

A brilliant green carabid beetle (family Carabidae) near the wetland.
A brilliant green carabid beetle (family Carabidae, species Chlaenius sericeus) near the wetland.

We’re almost ready for a lunch break, but as we’re walking back I notice a brilliant green beetle making its way among the damp gravels of the wetland. It’s a species I haven’t seen before, its legs deep amber and its wing covers coated with short, golden hairs. A closer look tells me that it’s a species of carabid (family Carabidae), a group of ground-dwelling beetles that hunt whatever insects they can catch.

Pygmy grasshoppers and meadowhawks

A pygmy grasshopper (family Tetrigidae).
A pygmy grasshopper (Tetrix subulata).

After our lunch break, we return to the search, making a loop around the other side of the wetland. A pygmy grasshopper leaps up from my path. It’s well-hidden against the mud. Smaller than my thumbnail, the top of its thorax is prolonged over its back into a slender point, a distinctive characteristic for this group (family Tetrigidae). These little grasshoppers eat mosses, algae, and decaying vegetation.

Striped meadowhawks (Sympetrum pallipes) laying eggs in the spikerush (Eleocharis).
Striped meadowhawks (Sympetrum pallipes) laying eggs in the spikerush (Eleocharis).

The meadowhawks are hard at work now, laying eggs. We stop to watch them, dozens of pairs, rising up and down in a quiet dance over a meadow of spikerush (Eleocharis sp.) ten yards from the water. They’re laying eggs here. When the water rises in the spring, the eggs will hatch. The aquatic larvae, voracious predators like the adults, will develop rapidly to bring forth the next late-summer spectacle, this hover-dance over the spikerush.

A giant water bug and a katydid

The giant water bug (Lethocerus americanus).
The giant water bug (Lethocerus americanus).

Now we’ve reached the edge of the water, and Glenn has spotted something he’s been looking for all day. It’s large, the size of a frog, rowing gracefully away from us along the muddy bottom. It’s a giant water bug! Intent on the water now, Glenn spots another and dives for it with a tiny aquatic dipnet. He comes up with a netful of mud – and the water bug!

The giant water bug (Lethocerus americanus).
The giant water bug (Lethocerus americanus).

We all work together to rinse the mud off. Kristi carefully holds the massive insect by the sides of its abdomen, avoiding the wicked sting it can deliver with its mouthparts. Another of the wetland’s voracious predators, this bug (Lethocerus americanus) doesn’t just eat other insects. Today we’ve seen several young common garter snakes (Thamnophis sirtalis) here, their yellow and red stripes contrasting vividly with their jet-black scales. Watch out, garter snakes – Glenn says that even vertebrates this large can fall prey to the giant water bug.

A male katydid singing from a willow seedling.
A male katydid (subsequently confirmed as Conocephalus fasciatus) singing from a willow seedling.

An extremely high-pitched song has been tugging at my ears for a while now. It’s a rapid, mechanical trill followed by a series of ticks: a katydid of some sort. And based on my observations around Helena, I suspect this is probably a cone-headed katydid (Conocephalus fasciatus), a species that seems to like wetland edges. It’s not entirely clear whether these katydids are plant-eaters or predators (reports conflict). In any case, this one is singing very close to us.

I get down on my knees, trying to track the sound. Then I spot it. The katydid is literally a foot from my ears, singing from the stem of a willow seedling. I can see its forewings quivering as it produces its shrill song. 

All the insects of the Rock Creek Confluence

A predatory sphecid wasp (family Sphecidae, probably genus Sceliphron).
A predatory sphecid wasp (Sceliphron caementerium).

Isn’t this enough insects for one little restoration area?, you might be asking. No – in fact, I’ve been leaving out a lot, trying not to make this too wordy.

But one more still deserves a mention. We notice a large, slender wasp that keeps landing on the mudflats near the giant water bug’s shallows. It’s mostly black, with crisp yellow trimlines. Its abdomen is mounted on a long, slender pedicel. It’s a predatory sphecid wasp, a mud dauber in the genus Sceliphron. Its prey: spiders. And what’s it doing here? Presumably, it’s gathering mud for another nest cell. It will fill the mud nest with spiders for its young to eat.

As adults, sometimes it’s easy to forget how amazing life is. But being out here, learning together and being in awe of the complexity around us, I remember the enthusiasm and curiosity I had as a child. As Kelly Dix remarked today, “it’s fun to be ten years old out here.” To be out with a group of passionate naturalists, celebrating the beauty of the world around us and helping with a wetland restoration project: I couldn’t imagine a better way to spend a day.

10 Replies to “Amazed by insects: a day at the Rock Creek Confluence”

  1. That was so much fun! I just found one of those giant water beetles in my little backyard pond! Probably eating the baby goldfish..🤔

    1. Hi Jenny, good to hear from you! Yes, what an awesome day! It was great to meet you. Very neat that you found one of those water bugs in your pond… hopefully the goldfish survive. 😀

    1. Hi Jo!

      Generally speaking, damselflies are smaller, more delicate-bodied, and have their wings folded together over the back at rest (or half-spread in a V). Dragonflies tend to be larger and more robust-bodied, and they keep their wings spread out at rest.

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