Chapter Six – Bugs & Natural History
In February, Dr. Gerald E. Brust (Gerry), a specialist in IPM (Integrated Pest Management), introduced himself to our class by exclaiming his pleasure at teaching folks who would be interested in learning about how to carefully, proactively interact with the insect world, instead of his usual audience, which asks two questions: “What is it?” and “How do I kill it?” Gerry’s approach is one of first learning about the insects and then deciding if they need “management.”
With his guidance, we first learned about arthropods (jointed appendages, exoskeleton) and then reviewed a variety of insect groups and their characteristics, from arachnids (spiders) and opilionids (“daddy long-legs”), to myriapoda (centipedes, millipedes), hexapoda, and detritivores (yup, they eat detritus, also known as waste). We explored the layers of the exoskeleton, why insecticidal soap might work, and the wild shapes that the exoskeleton can achieve.
Although the Latin names look intimidating on the written page, Dr. Brust enlivened his
discussion with slides, interactive questions, and acting out various differences between the groups. The lecture went on to consider molting and metamorphosis, with a few new vocabulary words (instar = stage). We turned our attention to the orders of hexopoda that are considered “pests” and began to gather tools to determine whether a pest needs to be dealt with or can just be left alone.
Gerry presented some interesting stories about four very creative approaches to survival in the insect world:
- Henrietta Homoptera, from the aphid family, hatches live clones of herself in the
summertime. When the plant she is living on starts to deteriorate, Henrietta alerts her embryos to molt with wings. In the fall, instead of live-birthed clones, her babies are now eggs that can develop into either males or females. Her eggs can overwinter—since she thrives on the plant she chose, her clones are likely to do well on it as well.
- Lorena Lacewing lays her eggs on long swings, primarily to prevent her children from eating each other (cannabalism of siblings)
- The Terrorful Tachinid
So, my little caterpillar children, beware ye the terrible tachinid, hidden in the guise of a large housefly, who will creep close to you at night and lay her eggs near your head . . . her child will grow inside you and take over your nutrition and, indeed, your mortal soul. And, just in case that’s not enough for you to fear, there is a wild willful wasp (a hyperparisitoid) that will lay its eggs so that they can feed on the tachinid larvae. Any hopes you had of surviving the tachinid invasion will be dashed by the developing wasp larva.
- The Hall of the Mummified Aphid
Aphids beware—as you walk along a common hibiscus plant or stroll along a calendula, happily feasting away, you may turn out to become lunch for a tiny wasp. You may see that there are many eggs that look like your cousins, but beware, many of these are actually MUMMIES that have been invaded by the larvae of brachonid wasps and, when they hatch, rather than being a relative of yours, they are a neat little clone of Aphidius!
After a lunch break, we were joined by Dr. John Seidel from the Center for Environment & Society at Washington College. Dr. Seidel is a colleague of last month’s lecturer, Dr. Wayne Bell. Dr. Seidel’s topic was “natural history,” focusing on the Chesapeake Bay and how humans have interacted with the bay over millennia. I was thinking that this would be more of the geography/geology and that I wouldn’t be all that interested, but he was captivating!
The lecture moved along swiftly, as he had to cover 18,000 years of history in less than 3 hours, but his enthusiasm for the topic carried us all along with him. His focus on the search for patterns from the past, with an emphasis on technology (which can be defined as anything from a sharpened stick to the space shuttle), helped tie all that history together. We considered the influx of saltwater and its ebb and flow over the years and how that has impacted where humans settled, what they did when they were on the bay shores, and the effects of climate change.
Some of the lessons are starting to echo from different lectures and different topics—for example, how Native Americans didn’t just coexist with the land, but actually modified it rather radically; and the importance of the edges and interfaces between different ecosystems (forest and field, bay and tidal marsh).
I was fascinated by the idea that the evolution of pottery could have an impact on the birthrate—if you have a way to cook mush in pots and feed babies, you might wean them earlier, which means that fertility rates rise. Another impact on fertility might be the change from lots of protein in the diet to more grains (carbohydrates), which changes the menstrual patterns in females.
Another section of the lesson was “carrying capacity” and how humans took natural constraints of this area and used cultural techniques to increase that carrying capacity. Dr. Seidel revisited the Jamestown colony (and other early European settlements) and explored the reasons why so many of them failed—including the 1609-1610 “starving winter” (partly due to the worst drought in millennia and the little ice age) and the bad luck of choosing a place on the James River where the river didn’t naturally flow away from the colony, resulting in the water becoming more and more contaminated with human waste.
Why did colonists keep coming back? A death rate of 90 percent should have been enough to discourage further groups, but the draw of tobacco and the wealth it represented was enough to keep Europeans trying again and again. Dr. Seidel likened this to the later California gold rush—and then slavery comes in when economically feasible—forced labor soon supplants indentured labor. The Virginia colonies used impermanent architecture—after all, you’d be making your fortune and then returning to England in a few short years—why build more sturdy structures?
Dr. Seidel then discussed some of the Eastern Shore farming development, as Maryland farmers switched from tobacco to grain, to fill Philadelphia demand—Philadelphia was a major shipping port for the Caribbean slave trade and the Mediterranean. We went on to consider the changes in technology, using arbitrary examples to fill out his theories. Topics covered included iron ore furnaces, metalworking the steam engine and the shipbuilding industry, the “interconnectedness” that was made possible by the Chesapeake & Ohio canal, the B&O Railroad, interstate highways, and the delights of creamed possum with sweet potatoes garnished in coon fat gravy (canning and its impact on the American diet).
Our class finished up with a lovely presentation by Roger Tilden, himself a Maryland Master Naturalist, who encouraged us to participate in the upcoming “Humboldt Project” (a way to use different learning styles to explore naturalist topics), followed by descriptions of three potential areas where we novice naturalists could get involved AND meet our requirements to complete a “project.”
And, just in case I hadn’t gotten quite enough of nature for one day, I chanced upon this fellow as I was walking across the pedestrian bridge at Adkins Arboretum. Happy Spring!
by Beth Lawton
Maryland Master Naturalist in training