The Heritage Herb Garden at the Ozark Folk Center State Park graces the grounds with visual colors and textures, sweet and pungent aromas, and helps us to interpret the history of the human use of plants.

 

This season has been a roller coaster ride for tomato gardeners. This spring, into summer, we had record rainfall and cool temperatures. The beds had to be well drained to support tomato life. Then it turned off hot and dry for a couple of weeks. This helped the tomatoes make fruit. Then the temperatures cooled down just a bit, which allowed the fruit to ripen. Just when it looked like smooth sailing, hornworms hatched out. In just two days, these hungry monsters ate their way through most of the tomato foliage and several of the green fruit in the Kitchen Garden.

Tomato hornworms, Manduca quinquemaculata and their close cousins, tobacco hornworms, M. sexta, feed on plants in the solanaceous or nightshade family. Though they prefer tomatoes and tobacco, these huge, lime green caterpillars also live on horse nettle, jimsonweed and deadly nightshade. The breeding form of these creatures are the hummingbird moths, also known as sphinx moths that delight those who watch them pollinate evening primrose, phlox and four o’clocks.

After mating, the female moths deposit their eggs on the tops and undersides of nightshade family plants. The eggs are smooth in texture, iridescent, pale green to white in color and oval shaped. They are deposited one at a time with space between them, rather than in a cluster. These can be brushed away or rinsed off of plants with strong streams of water if the gardener is watchful. The egg stage averages only five days and the eggs are hard to see.

The eggs develop into ravenous caterpillars that are tiny, at first. This is the time to apply organic pesticides. Diatomaceous earth, also called DE or diatoms, is a white or off-white silica powder that is the remains of microscopic algae that lived in fresh water lakes. The material kills soft bodied insects because it is microscopically sharp and pierces the exoskeletons causing dehydration and absorbs the oils and waxes that protect pests. It is safe for mammals to ingest. It is mixed in stored food grains as an anti-caking agent and is a fine abrasive substance used in toothpaste.  Wear a dust filter to avoid inhaling the powder when applying it to the leaves. There is a danger of killing bees and other pollinators on tomato flowers when dusting with DE. Bt, Bacillus thuringiensis kurstaki is a pesticide that targets only caterpillars. It is a bacterium that causes gut rupture in all caterpillars. Be careful to use this only on vegetable crops to avoid harming butterflies.

The green, feeding caterpillars are difficult to spot on tomato plants. Look for fresh, dark brown clumps of frass (insect excrement) when tracking them. The best time of day to hunt hornworms is in the evening. There are a variety of battery-powered lights that can be secured to the head with a strap or clipped to a cap brim. My friend, Nick, uses a headlight that has white or red light. He selects red to shine on his tomatoes when checking for hornworms. The pests are very easy to see under that light and can be picked off and stomped, dropped in alcohol or deep water or thrown hard and far away. If you find hornworms with tiny filaments in a row along the top of the bodies, let them live. They won’t be eating because they are being eaten by the larvae of parasitoid wasps. We need more of these on the planet. By the way, the horns on the back ends of hornworms are only there to scare you.

The caterpillars feed until they fall to the earth and burrow under to pupate through the winter. The pupae can be as long as the palm of the gardener’s hand. They are bronze to dark brown in color. The abdomens are segmented. The rears are pointed and the front ends have two, large, compound eyes and a looped appendage which is the proboscis. I have to squish these when I turn them up in the vegetable garden. If I don’t see you in the future, I’ll see you in the pasture!