Violets are the only food of the fritillary butterfly caterpillar
The fritillary butterfly lives its larval stage dining only on violets. The best food for the fritillary in our neck of the woods is the violets that evolved in our neck of the woods.
Fritillaries can be easily confused with monarchs because of similar coloring and markings. But they’re typically without the striking band of markings at the back edge of their wings that monarchs have.
There are many species of fritillary across much of North America. They fall into two major types: the greater (larger), with the genus name Speyeria, and the lesser (smaller) with the genus name Boloria. All of these rely on violets for their existence.
But here’s an outlier, the Gulf fritillary, the only species of the genus Agraulis. It eats eats only passion flower vines.
Remember that the violets are for the caterpillars to eat. Once they’re adults, they only need nectar from flowers, and sometimes minerals from mud.
The fritillaries that live right in our area here are: Callippe fritillary (Speyreria callippe)-living in the western area and downslope from Grass Valley and Nevada City; the Pacific fritillary (Boloria epithore)-from town and downslope and up in higher elevations; and the Gulf fritillary (Agraulis vanillae)-Nevada City and downslope (where there must be a lot of passionfruit vines?). And there are more that live in the lower and higher elevations.
During the recent mega-drought, the fritillaries were declining in numbers (while the Gulf fritillary, surprisingly, increased in numbers and distribution—an outlier).
The habitat of both the native violets and the butterflies is constantly getting whittled away by development, invasive weeds, and fire suppression activities. And the changing climate is further threatening them.
But not just your ordinary violets
What so many people have in their yards is the common violet, Viola odorata, from Europe and Asia. It’s a downright pest. It spreads aggressively by its running roots and its little seed pods spew zillions of tiny seeds.
But the flowers are wonderfully fragrant, and they’re edible, too. Even the leaves can be eaten when young. And, while not optimum, they might be able help us out on our efforts to keep our fritillaries going.
The best violets are the natives
We have many native violets, which aren’t so aggressive but are just as tough and beautiful.
There are three species of violets that are native right here in our area: Mountain Violet (Viola purpurea)-fairly common all around here, yellow flowers; Goosefoot Violet (V. purpurea purpurea)- yellow flowers; Douglas Violet (V. douglasii) –yellow flowers; and the Dog Violet (V. adunca)(shown)- purple flowers, grows at a little higher elevation.
Getting those special violets… for the diligent gardener, start with seeds
Unfortunately, according to Calscape.org, there are few nurseries that carry native violets. But there’s one seed company, Sierra Seed Supply, located in Greenville, CA, that carries some species of violet seeds, including Douglas Violet.
So the diligent gardener can try. I just may try myself. I’ll let you know if and when they’re ready.
I like to start my seeds in Speedling trays, flats with small, deep cells. I would start violets just barely covered with soil and keep them outside in late winter so they get alternating warm days and cold nights to help them germinate. But I’d protect them from frost. That’s my best guess so far.
The Dog violet is grown by Suncrest Nursery, which means you may be able to get it through your local nursery. But be prepared, for a special order you may need to buy a whole flat.
The other crucial ingredient to help those caterpillars
In late summer the female frtillaries lay their eggs in leafy debris. They don’t necessarily lay them near violets but they do lay them in the types of spots that violets would grow in. They attach their eggs on the underside of fallen leaves. In the spring, as the violet leaves grow, the eggs hatch and the baby caterpillars make their way to the violet foliage…hopefully.
The females each lay about 200,000 eggs placing them in several spots in the hopes that they’ll be near violets. But they’re pretty good at sniffing out the violets, by roots and foliage! They lay so many eggs they feel (genetically) that they can afford a haphazard approach.
So think about that when you’re raking or blowing leaves from around any violets you have. You may be removing and destroying many potential fritillaries.
Your violets may help; here are a few tips on what to do
Many individuals and laboratories successfully raise fritillaries on Viola odorata, the common perennial violet, and even on Viola tricolor, which is the pansy. But from what I’ve read in some of the scientific papers on fritillary research, these two species do not offer the best nutritional profile for the little caterpillars. They need to eat far more than normal to get enough of certain nutrients.
So while the fritillaries can survive on the common, non-native violets, the long-term solution is to be sure the native violets are abundant enough. If you have a patch of native violets on your land, avoid weed-whacking them. And don’t “clean” them up by raking, they need those leaves around them for eggs.
If you have common violets, think about keeping a patch that can be maintained just for the fritillaries. Leave a leafy mulch around them. And keep it in bounds by cutting back the running roots in summer, before those eggs are laid.
If you notice holes in your violet leaves you just may be feeding this pretty butterfly. But you won’t see them, because they only come out to feed at night. During the day they go back and hide and rest in the leafy mulch you left there for them.
See Calscape.org and check to see the violets that grow where you are. There are good photos to help you identify them. Then you may be able to spot them on a hike. And collect seeds, maybe?
Calscape.org also has good photos of all the fritillary butterflies in California.
Another great resource is the Redbud Chapter of the California Native Plant Society’s book Wildflowers of Nevada and Placer Counties, 2nd ed., available at local book stores.
Go out and take a hike and see if you can find any native violets this spring and summer. And watch for fritillary butterflies.
Photo credits: Nancy Gilbert