Fuzz on the Ratibida: a mystery

Every summer I eagerly await the return of the Gray-headed Coneflowers (Ratibida pinnata), not just because they are beautiful and prolific bloomers, but also because they host a huge variety of pollinators and other insect life—including my beloved Camouflaged Loopers. 

Said loopers are one of the reasons I will stop and closely inspect any slight aberration on the head of a flowering Ratibida. Sometimes it is just an errant yellow ray floret, twisted up at an angle, or a sneaky ambush bug lurking until its unsuspecting lunch shows up, or maybe some warty-looking galls. But on lucky days, I find a little Camouflaged Looper in its petaled finery. 

Last summer I noticed many Ratibida that had clumps of yellow thready material tangled among the brown disc florets: 

It appeared as if the pollen-carrying anthers (stamens?) from the florets had been pulled out and collected together in a mass. What was causing this phenomenon? Could a bee or other pollinator be collecting them, purposely or inadvertently, and discarding them as they snagged on the florets?

Stumped, I took my question to the IOWA-NATIVE-PLANTS listserv (always an amazingly friendly and helpful group), which yielded several theories but also a general puzzlement as well. Perhaps a bit of webbing was visible that would indicate an arachnid origin, or maybe some kind of fungal growth? But alas, no definitive answer surfaced. After a stretch of rainy weather, I failed to locate the mysterious clumps again for closer inspection that summer.

Skipping ahead to this summer, around the same time, I again found the yellow clumps during routine Ratibida inspections! This time, I broke off one of the flowerheads and brought it home for a deep dive into the mass. With my trusty 10x magnification loupe, I thought there might be something visible beneath the fuzz, just a hint of something pale amid the brown florets:

Gently teasing away the threads caused whatever was under them to retreat into the forest of florets. A tiny worm! Caterpillar? Something....

Again gently, I prodded the critter closer to the surface for a better look. Definitely a caterpillar, and did it have bits of pollen and florets stuck to it? Could it be....a super-tiny early Camouflaged Looper?!

iNaturalist's suggested ID supports the suspicion. The Camouflaged Loopers I'd encountered previously were small—maybe 1.5 cm long?—but readily visible. These? Super tiny. Each of those brown disc florets in the photos above are maybe 1 mm across, so the caterpillar itself was perhaps .5 cm? 

What caused it to collect the yellow thready clump? Was it a purposeful effort at concealment? Or maybe more likely did the threads just snag on the assorted protuberances and edges of the caterpillar's body as it moved around the flower? Or was excavating the caterpillar beneath the fuzz merely a coincidence, and the fuzz was caused by something else entirely?

I'll have to again be on the lookout for bits of fuzz on the Ratibida to see if the discovery can be replicated. Regardless, what a fun demonstration of what there is to see right along the trail if you slow down to look!

Note also the even tinier critters scampering around the Ratibida florets!

Sources/Additional Reading

• The Prairie Ecologist: My favorite insect further endears itself to me
• Missouri Department of Conservation: Wavy-lined Emerald
• BugGuide: Species Synchlora aerata - Wavy-lined Emerald

No such thing as a free lunch...

 

Beetle socks? Clown shoes? What is going on with this Margined Leatherwing's little feets and their coordinating attachments?

With difficulty, it walked along the leaf margin like a dog reluctantly wearing shoes, lifting and shaking its legs in an attempt to unencumber itself from these orange globs. 

For a bit, it attempted to use its mandibles to loosen them...

with limited success, before with a short flight returning to the source of its discomfort:

Beautiful, fragrant Common Milkweed flowers have a fascinating structure. Upon blooming, the petals of the flower fold downward, forming a kind of skirt below the corona, which is where all the action happens.

Each corona has five "hoods" that hold the nectar pollinators so desire—nothing tricky there. But in between those hoods are slits into which the leg of a butterfly, fly, bee, or beetle may slip. When the leg is pulled out, it may catch a structure called the corpusculum, from which dangle a pair of pollen packets called pollinia. 

If an insect successfully extracts its leg, pollinia and all, its continued foraging on other milkweed flowers will hopefully (for the milkweed at least) bring the pollinia into contact with another slit. A pollinium thus delivered can slip into the "stigmatic chamber" contained inside, where it will make contact with the stigma and fertilize the flower.  

This process can be dangerous for the insect: sometimes their leg may become stuck and they may lose it...or even perish if they are unable to get free. Our Margined Leatherwing, fortunately, has so far escaped that fate.

Sources/Additional Reading:

• The Story of an Organism: Common Milkweed
• Milkweed Pollination: A Series of Fortunate Events

A shortgrass prairie plant in a tallgrass prairie state

A little tumbling flower beetle (Mordella spp., tentative)
on a spike of Buffalograss.

As you walk along the trail, look down and you're apt to see the flower spikes of low-growing Buffalograss, a beautiful native grass with fine blades that may have more of a blue or gray tinge to them than the surrounding grasses. 

A drought-resistant denizen of the shortgrass prairies of the Great Plains, Buffalograss tops out at around five inches — quite a contrast to the flashy tallgrass specimens of Big Bluestem or Indiangrass, both of which regularly reach six feet tall. It is an important food source for bison and other mammals, hence the common name, and many grasshoppers, including the Admirable Grasshopper, Syrbula admirabilis. 

What a pretty grass!
Male flowering spike of Buffalograss.

Buffalograss is generally dioecious, meaning male and female flowers are found on separate individuals. The conspicuous male flowers are held above the grass on short spikelets, which are arranged on a spike that has been described as resembling a comb or eyelash. To see the female flowers, you have to get down on the ground and look closely (so closely, perhaps, that your behavior prompts a kind passing cyclist stop to make sure you aren't in need of assistance). The seed-producing female flowers grow closer to the base of the plant, with reddish-purple styles to catch the wind-distributed pollen from those male flowers up above. 

Most other grasses hold their seeds high above, making for easy distribution. Why does Buffalograss tuck theirs way down low to the ground? Some sources mention that the low profile helps prevent the seeds from being munched and destroyed by the bison and other browsers who find the grass so palatable. Other sources note that its placement encourages consumption by bison, whose digestive process helps break down the seed's coating, and deposits it in a rich bed of fertilizer. 

Tiny, hidden female flowers of Buffalograss grow low to the ground.

Sources/Additional Reading

• Illinois Wildflowers: Buffalo Grass
• Minnesota Wildflowers: Buffalo Grass
• USDA Plant Guide: Buffalograss
• A Wandering Botanist: Plant story: the amazing buffalograss, Buchloë dactyloides