Somehow we missed this in July. We posted the article on our Facebook page. Have you visited AND LIKED us at UC Master Gardeners of Napa Valley? Please do!
We missed posting this to our blog. Penny Pawl, our extraordinary butterfly caretaker, explains how planting fennel led to so much else in her garden! You will notice a change in the font size partway through the article. The original does not have this change. I have tried to change it on this page, and have resized the original twice, to no avail. It posts those paragraphs in enormous font size. Think that's why it was skipped--because I couldn't fix the font.
Fennel is a Mediterranean plant that has been introduced to the United States. Over many years, it has naturalized in our area. Recently I saw an anise swallowtail butterfly visiting my fennel (Foeniculum vulgare) so I went out and looked for eggs and babies. The babies look like bird droppings as they are black with a white strip through their middle. In this search and subsequent ones, I discovered many small bugs living in the fine leaves of the fennel.
I originally planted this fennel to attract butterflies. The anise swallowtail is a beautiful yellow and black butterfly that especially likes the nectar of lily-of-the-Nile (Agapanthus). A few years ago, I was raising four anise swallowtail larvae and suddenly all but one died. I continued to watch the survivor until, one day, a small larva hatched out of his side. Then the caterpillar died.
I decided to observe what the larva turned into when it hatched. It was a small parasitic fly, and it had laid the egg before I had collected the caterpillars.
Butterflies of all species have a rough time laying eggs and raising them to full-size adults. That's why I take the time every summer to raise as many larvae as I can in my house. As soon as they pupate, or hatch, I let them pump up their wings and leave.
As I worked my way around the fennel, I found two tiny black-and-white spiders. Each one had created a web, and as soon as the spider caught an insect, the insect was carefully wrapped in the web and stored for the future. Both of these guys stayed close to their catch to guard it. They left only to gather more insects.
The one bug that puzzled me was an almost-yellow stink bug. Although I am always watching bugs, this one was completely new to me. over several days, I observed him. He moved to my milkweed plants, which concerned me, so I captured him in a jar.
I was finally able to identify the bug as a redshouldered stink bug (Thyanta pallidovirens). It is considered a good bug compared to many stink bugs and the invasive brown marmorated stink bug (Halyomorpha halys). Most stink bugs feed on and damages plants while the redshouldered stink bug eats other insects. All stink bugs have a straw-like mouth, the brown marmorated stink bug and plant feeding stink bugs carries theirs down their stomach and the redshouldered stink bug has his pointed forward. I did observe him sucking on a dead bug but a live insects would be his preference.
As my fennel is finally preparing to bloom there are many small flies and wasps visiting the buds. The swallowtail caterpillars are growing. In fact one has already left the pupa and is hopefully laying more eggs.
To raise the caterpillars in the house, I collect the eggs or very small caterpillars and put the them into small containers. When the eggs hatch the caterpillars are about 1/8 inch long. I add more fennel daily and clean ou their droppings. After shedding and eating their skin four times, they change from black and white to green with yellow and black markings. By this time they have tripled their size. (This size increase is common to all butterflies in the swallowtail family.) This amazing growth rate is the reason they shed their skin. After turning color, they eat without stopping. I have to transfer them to a larger container and I feed and clean their droppings twice a day. All they leave is fennel stems stubs.
Before the form a pupa, they go on a walk around the container. Once they settle down, it is a few hours before the skin covering opens for the last time revealing a pupa. This will be their home for weeks or even months. Most will spend the winter or "overwinter" in the pupa and emerge in the following spring to begin the process over again.
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.