HOUGHTON – Spring may be playing had to get this April, but the first butterflies of the year might have already taken flight.

Winter is a generational gap for most butterflies, said Michigan Tech professor and amateur butterfly enthusiast Tim Isley. Mourning cloaks, however, are some of the longest-lived butterflies in the world, and their reward is to spend their winter alive in a protected hideout, waiting for the very first signs of spring.

“Because they’re black, they use solar heat, and they’ll start flying as soon as there’s sap running to drink,” said Isley.

By the time the leaves and flowers come out, the mourning cloaks will have laid their eggs, and new caterpillars will be hatching.

Isley spoke about butterflies and favored foods that can attract them Monday at a Keweenaw Garden Club meeting at Portage Lake District Library.

Since 2007, he said, he’s been photographing and writing about U.P. butterflies on his blog, somethingscrawlinginmyhair.com.

In the U.P., Isley said, there tend to be more butterflies in the forests and fields than gardens, but thinking outside the box about plants can draw some fluttery friends.

Tansy, for example, is generally considered a noxious weed, he said. For painted lady caterpillars, though, tansy is a perfect lunch.

“This was a surprise, because nothing eats tansy,” Isley said.

Painted ladies, he said, migrate north to south following the weather, but they’re unusual in that the migration takes many lifetimes, with each generation flying a short leg, then laying eggs.

There are also some herbs and plants that are irresistible just to a particular species, like fennel for black swallowtail caterpillars. So what if you’ve already got fennel, and you’re curious if those caterpillars you see will turn into swallowtails?

“If you poke them, they’ll stick out these horns and smell terrible,” Isley said.

With cabbage white butterfly caterpillars, it can sometimes be hard to decide if they’re a blessing or a curse. To begin with, they look like earwigs, Isley said, even if their adult stage is more attractive. Around here, they are not after cabbage – they are more likely to eat broccoli leaves.

Jean DeClerk, president of the Keweenaw Garden Club, said she lives in a pretty butterfly-friendly neighborhood and does not plan to plant anything special, but it’s great to know more about what she might find.

“Just pay attention, see what’s in your yard,” she said. “For me, the point is to enjoy the butterflies that are already there.”