The Bug Days of Summer
By Grace Grattan, Phase II Fellow
My first draft of this blog turned out to be a long-winded breakdown of the complicated relationships between humans, plants, and insects. As interesting as it was to analyze each relational component and their histories with each other, it was enough for a book and way too much for a blog post!
Yes, I think about bugs a lot.
With that being said, I think insects are either largely ignored by humans, eradicated as creepy, destructive pests, or lucky enough to be lauded and protected as beneficial pollinators. Taking the time to observe, learn about, and ultimately understand more about our insect neighbors is an interesting (and I would argue, beneficial) exercise in perspective. I think this is true not only for small vegetable farmers, who are forced to coexist with insects but also for anyone who consumes locally grown produce. To hopefully kick-start some curiosity in you readers, I thought I’d introduce some of the insects I’ve met this season on the farm.
We planted as many flowers as we could around the farm to attract pollinators, as part of our cut flower operation, and even as a trap crop. All throughout the season, bees of all kinds were buzzing around the flowers. The dahlias we planted were a favorite with the local bumblebee population. Contrary to popular belief, bumblebees do sting and can do so repeatedly without dying. I learned this the hard way while grabbing one trapped in the high tunnel in my fist. The already panicked bumble thought she had to fight for her life and stung me in the finger as I threw her out.
Early in the spring, we thought we spotted monarch caterpillars on our dill and parsley! It seemed a little early for monarchs, so I did some research and it turns out we had a population of black swallowtail butterfly caterpillars! Like monarchs, who dwell mainly on milkweed host plants, these black swallowtail caterpillars mainly hang out on (and devour!) host plants in the Apiaceae family (e.g. carrots, dill, fennel, parsley).
Of course, monarchs deserve their own shout-out! Like last summer in Highland, I noticed two “waves” of caterpillars and butterflies on the farm. The first occurred earlier in the summer, around mid-late July, and one happened later in the summer/early fall, just as I am writing this post. It’s so exciting for me to see monarchs flapping around the farm and I always do my best to spare the milkweed for them while I’m weeding. Milkweed is also a host plant to many other species of insects, including these fluffy milkweed tussock moth caterpillars and this red milkweed beetle (below). In the height of the season, it seems like each leaf of a milkweed plant is home and dinner to a different species of insect!
Throughout the summer I’ve watched our high tunnel praying mantis get bigger and bigger! She started as a little inch-long twig and is now almost as long as my hand. As praying mantises are territorial, she has watched over our high tunnel all summer and has no doubt helped quite a bit in keeping pesky insects away. Praying mantises have evolved what’s known as a metathoracic ear. This allows them to detect and respond to ultrasound frequencies, which assists in avoiding bat’s echolocation predation from bats.
When growing tomatoes, a huge pest can be the tomato/tobacco hornworm. These caterpillars can get as long and thick as a person’s middle finger and will do some real damage to tomato plants. We pulled one off a plant a month or so ago, but in the past week, we have noticed other tobacco hornworms in the high tunnel that have been parasitized! These unfortunate caterpillars had been injected with the eggs, and eventual larvae, of a braconid wasp. The eggs hatch and the larvae eat the caterpillar from the inside out, which is pretty disgusting and horrifying if you’re a hornworm, but great if you’re a tomato farmer!
These highly specialized braconid wasps are a part of the larger braconidae family of parasitic wasps. The family includes wasp species that have evolved so specifically with a certain host that the wasp lays her eggs inside the host even as it releases a virus that attacks and suppresses the host’s immune system so that it won’t fight the foreign objects that have been inserted. Terrifyingly ingenious!
Recently, I’ve noticed quite a lot of yellow garden spiders, which are orb weavers. They have taken up residence in the cut flower row, in the high tunnel peppers, and even in the cherry tomatoes. Their webs are beautiful and their striking black, yellow, and white coloring (and large size!) can catch you off guard while harvesting. I always find myself stuck between rooting for the spiders and also wanting the unsuspecting flying insects to evade their webs.
These are only a small handful of the insects I’ve met this season on the farm. They never cease to amaze me, brighten my day, and have incited so many research wormholes!