By Penny Pawl, UC Master Gardener of Napa County
The tomato hornworm that so many gardeners detest has a beautiful future if we let it be. After a winter spent underground and when it is done with metamorphosis, it will become one of the loveliest and largest of the moth species.
We never get to see this moth because it only flies after dark. It is known as the sphinx moth or hummingbird moth. Some of them fly in a manner similar to the hummingbird.
During metamorphosis, a caterpillar transforms into a moth. The caterpillar's internal parts liquefy, reform and a moth is born. The same happens to butterflies and it is one of miracles of nature.
I found three of these giant worms the other day munching happily on one of my tomato plants. They blend in very well with the plant, and they are as big as my finger.
I gently pulled them off and inspected their grinding mouth parts. Then I put them under a large overturned bowl with some tomato leaves and the tomato they had been chewing on. The bow is resting on the garden soil.
Most people get upset when they see hornworms on their tomato plants. I get excited. I hate losing my precious tomatoes to them, but by putting them in a container, I give them a chance to complete their life cycle.
Many people agree with me. We like hornworms because they assist with Integrated Pest Management, a way of gardening and farming that relies on the good bugs to manage the bad bugs without the use of pesticides.
Hornworms eat your tomatoes, but in turn, the beneficial braconid wasp lays its eggs in many of the caterpillars. These tiny wasps develop within the caterpillar skin and eventually will kill their host. They emerge from the caterpillar looking rather like rice hulls on the back of the caterpillar.
This same process happens in other butterflies and moth larva and helps with pest management. Anise Swallowtail caterpillars, which feed on plants in the parsley and fennel family, also have parasitic wasps lay eggs in their eggs.
When the caterpillar completes its life cycle and transforms into a cocoon, it will drill into the soil to spend the next several months. I watched one do this and it was gone so quickly I was amazed. The following summer, when the weather warms, they will hatch and begin to fly around looking for places to lay their eggs. Tomato plants are a favorite host, but they like any plant in the nightshade family, including peppers, eggplants and potatoes
I have read that marigolds, basil, borage and mint will repel tomato hornworms if planted alongside the tomatoes. Their strong odors seem to repel the moth.
The hornworm begins life as a small egg laid on the underside of the leaf. The larva hatches and grows quickly, and as it grows it eats more and more of the host plant. After three to four weeks, it is ready to take that dive into the soil.
I raised two hornworm larvae in the house in a container a few years ago. The hornworms spent the winter in my refrigerator in a small jar with soil. When summer arrived, I moved them to the garden, but I fear the experiment was a failure. The three giants I just collected will be on their own when they decide to go into the next part of their life cycle.
UC IPM has this Pest Note on Tomato Hornworms:
The UC Master Gardeners of Napa County are volunteers who provide University of California research-based information on home gardening. To find out more about home gardening, upcoming events or to submit gardening questions, visit the Master Gardener website (napamg.ucanr.edu). Our office is temporarily closed to walk-in questions, but we are answering questions remotely and by phone or email. Submit your gardening questions through our website, by email firstname.lastname@example.org or leave a phone message at 707-253-4143. Master Gardeners will get back to you within a few days.
In recent years, the plight of the honeybee has made international headlines due to alarming colony losses. When many folks hear the term pollinator, the honeybee quickly comes to mind. While honeybees are indeed an invaluable pollinator resource, there are many other pollinator species with interesting stories.
For example, Syrphid flies (Syrphidae) are intriguing garden guests. Also known as hoverflies, they are contenders for second place after native bees as important pollinators. In fact, many look remarkably like bees and wasps and reveal their identity only upon close inspection.
Attracting hoverflies to your garden has an added benefit: many of their larvae are important in controlling aphids. Peaches, plums raspberries and strawberries are just a few of the edible crops they pollinate.
Moths are another important pollinator. When bees retire at the end of the day, many species of moths take over the night shift. With a preference for light-colored and fragrant flowers, they are top-notch pollinators for gardenias, tobacco and morning glory.
Many moth species rival butterflies when it comes to beautiful markings. To help keep them in your garden, reduce or eliminate unnecessary bright lights, which can disorient them.
Bananas, mangos and peaches are a small sample of fruits that bats might pollinate. Like moths, bats work the night shift. Several species of pollinator bats inhabit the southwestern
U. S. and Mexico, and some agave and California desert cacti depend on them for pollination.
The bats in Napa County are mostly insect-eating species. Some can easily consume several hundred insects, including mosquitos, in an hour.
Few people know that mosquitos are also a pollinator species. We malign them for spreading disease and causing itchy bites, but actually only the female bites. Males drink nectar—as do females—and transfer pollen in the process.
Wasps are critical pollinators for some fig trees, which are popular in our mild Mediterranean climate. While some modern fig cultivars can produce fruit without wasps, traditionally the fig wasp is the main pollinator. The female wasp lays her eggs in what will become the fruit and in doing so transfers pollen she has collected. She then dies and is resorbed by the fruit as it matures.
One other pollinator species often gets overlooked: humans. Yes, in many instances, we do the job by hand. Vanilla is perhaps the best-known example. However, some plants grown in greenhouses—such as tomatoes—are gently touched with an electric toothbrush to simulate the “buzz” pollination of bumblebees and release large amounts of pollen. This is an excellent way to boost production in your own garden.
Giant pumpkins—or any squash for that matter—can also be hand pollinated. While the method is a bit more involved, hand pollination can also be used to keep desired strains pure or to increase the likelihood of getting a crop at all.
Beetles, lizards, ants and even snails and slugs are all known pollinators, among many others. Planting different species of plants and growing flowers with different bloom periods can provide food and habitat for these essential creatures.
Also, planting natives and flowers known for nectar or pollen is a good strategy for attracting pollinators. Decreasing or eliminating your use of pesticides will also help. With summer weather in full swing, take a closer look at your garden. You might just find a few of these pollinators are already present.
Free Tree Walk: U. C. Master Gardeners of Napa County will host a guided tree walk of Fuller Park, 560 Jefferson, in Napa, on Monday, July 10, from 10 a.m. to noon. Enjoy a fun, informational stroll through the park, learning about its history and 41 different trees on site. Wear comfortable shoes. Restrooms are available and handicap accessible. The book Trees to Know in Napa Valley will be available for $15 each (cash or check only).
To register, call 707-253-4221. Walk-ins are welcome, but you are guaranteed to receive a complimentary map and additional information if you register at least 48 hours in advance.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.