Wild On The Prairie: Plants

A group of Purple Thistle teaches some children about ecology

Published Oct 1st 2000 in Plant Life

Recently while instructing a group of children on plant ecology, I was rudely interrupted by a Texas Purple Thistle. The plant kept jabbing spines into a girl crowding the group, to seek the shade the rest of us were enjoying. When she screamed in pain and frustration, the others turned around to see her source of irritation. She inadvertently cursed the thistle, and then thumped it to draw attention away from her impolite behavior.

I did not admonish her, and all the children, surprised that I did not, stood gazing at the plant, still waiting for the words of reproval. A child noticed a lady bug on the thistle, and reached out to catch it, saying, "ooooh, a lady bug, that means good luck!"

The thistle seemed to be dripping in lady bugs, and soon everybody had one in hand. I made the most of it. I found thousands of aphids on some thistles nearby and broke off a stem section with hundreds lining one side. The kids were grossed out.

"They look like little ticks that are stuffed and about to pop!"

"This is why the lady bugs are here. Look at the baby lady bugs."

"Those are worms -- not bugs."

"Lady bugs aren't bugs, they are beetles, and these are their larvae -- and look, here is one of their pupa."

'OOOh, this little bag? It looks like half-dried snot!"

I described how the larva of the beetle transforms itself inside the pupae. The kids would not let me squish one to see what stage the pupa had reached. Somebody else noticed a golden fly on the thistle. "Bee!"

Every kid took a step or two before I said, "Whoa. Take another look. This is a fly, it only has two wings."

Another fly was noticed -- a tiny red one shaped like a fruit fly, but bigger. Or was it a wasp, looking to parasitize caterpillars. Caterpillars? Oh, yes, dozens, hidden behind a curtain of webbing. The leaf was skeletonized under the webbing. One boy tore the web curtain, but the red fly/wasp did not come to the caterpillar six inches away. We bent the leaf to look at the tiny red insect more closely. Some of the kids said the critter had a "wasp waist" (a narrowing of the abdomen where it meets the thorax), and some said it did not. The critter flew away before we could settle the argument.

An ant clambered along near the mass of aphids. I informed the kids about honeydew. We could not see any globules of moisture at the anal end of the aphids. "This species of ant herds aphids, like we herd cows, and they drink the honeydew."

"OOoooh, gross --- eating bathroom stuff!" We looked again at the aphids. "Here's an ant licking an aphid's butt!"

The kids tittered nervously at the bold girl's comment.

"Here is that red fly back again." I noticed it perched on a wet spot on the undervein of the leaf. "I wonder if it coming to the honeydew." The kids were still watching to see if I would react to the girl's comment.

A big bumblebee came blundering into the thistle bloom surrounded by kids and me. They scattered. The presence of an animal or insect with a powerful defensive weapon is often interpreted as being an offensive act I growled at them. "Get back here! And then, hold still -- if you do not move, it won't get scared. Instead of fearing something and immediately killing it, respect and understand it."

They stopped and slowly came back, and watched as I poked a grass stem at the bee. "Look, he is covered with pollen. Do you see the "dust" on his hair?"

The bold girl crept closer. "What color is it" I asked her. Before she could answer, I continued, "Everybody thinks all pollen is yellow, but what color is this pollen?"

She leaned over until the bee felt her breath and it buzzed a little louder as it dug even deeper into the blossom. "It is sort of whitish, isn't it?"

I told them that the bumblebees nest in the ground and make honey pots. They did not believe me. "Bees live in hives," they said.

"Hives are for honeybees. Wild bees mostly live underground. Bumblebees have 20 or 30 adults living in one old mouse nest under a bush or rock somewhere."

A Black Swallowtail Butterfly tried to come through the circle of kids. I made some kids get out of the way so it could land on the thistle.

One child mused, "Are the caterpillars the babies of the butterfly?"
"Good thinking! But I forgot the answer. I want you to go find the answer when you get back to school, and call me. Find a butterfly identification book and look up Black Swallowtail."

"We do not have books like that in our library."

A kid who had attended the Sibley Summer Camp shook his head. " I wanted to show some friends I was not lying about the tarantulas throwing hair, and we went to the school library, and they had absolutely no identification books. We finally had to get a teacher to help us get on the Internet after school She did not believe me about urticating hairs, either!"

A dull colored moth nectared at another blossom. "A moth in the daylight?" One of the kids made a joke about enjoying a "midnight snack.

"Bumblebee moths are a kind of day-flying moth. They lay their eggs on gourd vines, but they nectar on thistles. They look like a bumblebee until you realize they have fuzzy antennae and do not buzz."

In the large multi-trunked mesquite next to us, a hummingbird chittered. "He wants to come to the thistles too. He will eat the tiny insects in between the stamens. This one "bloom" is really hundreds of individual flowers -- all daisies are composite flowers that produce hundreds of seed for each "flower head."

"When a thistle seeds out, Lesser Goldfinches come to eat them and gather the hair of the seeds to line their nests."

On cue, two perched on the barbed wire fence near us. One began fly-catching, darting out into a swarm of gnats. "This may not seem much to you, but it is to an ornithologist. We may be seeing something no one has ever noticed before, or at least published in any scientific article or book. Goldfinches are normally strictly seed eaters, except when feeding young. And these should not have young. Why is that?"

No one tried to guess why the Goldfinches should not have young yet. Another child found a pink crab spider in the bloom. l told her that some crab spiders can change their colors in 24 hours to match the color of the flower they lurk in. I sort of got in trouble with the kids' adult leaders-- we did not make it back to the Nature Center at the proper time. The group would be late returning to school.

Plants teach the interconnected matrix found within the landscape, so I am glad the Purple Thistle interrupted my planned talk -- it did a much better job!