Essays

Moseying: Exploring the Natural World

Chemistry lesson in the garden from a beetle
August 8, 2004

“I hate bugs! Icky, nasty bugs, biting bugs, covered with germs – bugs are bad!” I have had hundreds and hundreds – no, I have had thousands of kids utter such condemnatory words. It is not their fault – it is what they have learned from cautious parents, mostly ignorant of what bugs do as part of their life cycle. I make them catch bugs at the Sibley Nature Center, and after the bugs are safely in baby food jars, the kids usually become fascinated with their finds. Afterwards, I tell them short little stories about the bugs and their behavior. It is part of Sibley’s mission – “getting to know your home and all of what lives with us on the Llano Estacado.”

At home, at the Gone Native Arboretum, one early morning, after I spent a couple of hours doing routine maintenance, I sat in the shade with a cool mug of ice tea and a book. I keep my eyes roving, however, intermittently glancing around to see what has come to visit.

“Good morning, Ms. Canyon Towhee, you must have young since you are fussing at the new black kitty. And Old Lady Mockingbird, I see you are teaching your fledged young to proper technique to swoop upon intrusive felines. Mr. Cardinal, you are sure pretty, and I am glad you like the misting sprinkler in the flower bed – you brighten my day! Silly skittish whiptail lizard, you look funny holding all four legs and tail up as you warm your belly on the warm path. Mr. Yellowhead Turtle, what’s new in your world?”

In mid-July, I stopped by the Midland County Public Library to hear a presentation on Fort Lancaster, and then checked out some books. I got a book by Dr. Thomas Eisner, an entomological professor at Cornell University. Avid Discovery Channel viewers might remember seeing him on shows about arthropods and their chemistry.

It did not take me long to become intrigued with Mr. Eisner’s writing. I knew that plants often have interesting chemicals in their leaves, as defenses against herbivores. I was sitting next to a lemon verbena kin – Aloysia wrightii, or whitebrush. It has a sweet but tangy smell when the leaves are crushed (not “citrusy: like lemon verbena, but more like fennel or licorice.) And I knew about bugs and chemicals – everybody knows about monarch butterflies and milkweed. The milkweed gives them a bad taste, so birds do not eat them.

An Elodes beetle wandered out of the mulch under the whitebrush. I happened to be reading about them at that very moment! You know them, the black beetles that stick their “butt” up in the air and make a stink. Hundreds of kids at Sibley have laughed at me when I stick one on my nose, and many of them have then done the crazy stunt themselves after I do it. They have two large sacs near their abdominal tip that drip a brown liquid out through a gland. Benzoquinones make up part of the secretion, with three unsaturated hydrocarbons and caprylic acid.

The benzoquinones give the secretion its odor. The unsaturated hydrocarbons have yet a different odor, which somewhat masks the benzoquinone odor – in other words, the smell could be worse! The caprylic acid serves as a wetting agent, and increases the permeability of the chitinous exoskeletons of ants and other potential predators. Caprylic acid is an oil that has an affinity for the lipids that make up the waxy arthropod integument (shell.) The secretion spreads over an ant’s exoskeleton and then penetrates in a larger area, because of the caprylic acid.

Eisner’s book details the creation and execution of the experiments that determine the purpose of arthropod secretions. The creative solutions to demonstrate these purposes are amazing. In almost 50 years of teaching he has had hundreds of graduate students to aid him. All of his assistants are thoroughly credited, illustrating how scientific research works best as a cooperative affair.

I reached down and caught the little darkling beetle and perched it on the tip of a finger. It waved its front feet forward, and then slid them down to escape. I dipped my finger towards the ground, which stopped its movement. I waved my hand up and down until it became confused and remained motionless. Then I brought it up to my eyes, lifting my eyeglasses to my forehead, like an old man, so I could examine it closely. Its tiny antennae wiggled at me as I gazed at it. I love knowing something new about the creature! Learning about the caprylic acid explained why a brown spot on my nose from another beetle stayed on my nose for a week or more. Is caprylic acid added to ointments? I will have to look at my often used Ben-gay and cortisone cream!