If you want to attract butterflies into your garden you need to know something about their life cycle to appreciate that it is not only the insect, but also the caterpillar you have to consider. In the case of the fritillary I have discovered that the caterpillars feed on violets, hence the title. This comes from an article by Linda Thomas which I found over on The Master Gardeners website.

Until this summer violets were a plague in the cultivated areas of my garden. Under every expanding clump of the purple-flowering plants there were hundreds of tiny seedlings. The violets even prefer to grow mingled tightly with my perennials. Like most gardeners, I grubbed them out before they could take over.
As I was doing just that one sweaty day last August, a Great Spangled Fritillary butterfly (Speyeria cybele) gently settled among them and began laying her eggs. These are large butterflies, orange with black spots on their upper wings and pretty silver spots on the underside of their hind wings. They are among my favorite insects. Clearly, violets have a role that I didn?t know about. I needed to learn more.

The larvae of most butterflies feed on at least a few different plants, but Great Spangled Fritillaries depend exclusively on several varieties of violets, just as the more famous Monarch butterfly caterpillars dine solely on various kinds of milkweed. Without violets, I learned, these beautiful butterflies would not decorate our gardens. With such a restricted diet, their caterpillars are not garden pests, although violets do look tattered by late fall. The caterpillars feed at night and crawl away from violets to hide during the day. They are difficult to find, dark brown to black with black spines that are orange at the base. Even with a flashlight, I have never found one. But the butterflies live in my garden, and my violets are chewed. I think it?s a fair price to pay.

See more at The Master Gardeners