Our most common butterfly

The cabbage white is abundant in New Jersey. — Marcus Rahm/Creative Commons

Butterflies by now have shown up in numbers to flutter around the flowers and chase one another around the yard. I’ve got yellow and black swallowtails, loads of silver-spotted skippers and — I think — American ladies. But no species is as plentiful as the cabbage white, a bug I spent most of my life misidentifying as a moth.

There is a cabbage moth, a plain, mousy, gray-brown thing that flies by night and is seldom seen. And what we recognize as the common cabbage white butterfly can actually be one of two related species, the large white (Pieris brassicae) or the small white, (Pieris rapae).

It’s the large fellow, a habitué of sheltered spots like gardens that we are likely to know best, large being a relative word when you’re talking about a butterfly only one and a half inches across. The smaller fellow prefers open fields and is a bane of farmers.

On sunny afternoons when the wind is still and the air is warm, dozens of cabbage whites work the far end of my garden where the purple coneflower and salvias grow thick. From afar, they look like a cloud of confetti; up close, they are so densely congregated and so intent on their buggish business that they often bump into me, harmlessly ricocheting away.

No doubt you’ve noticed these guys — their wings are white on the top surface with a sooty gray tip, creamy or pale yellow below. You can easily tell the girls from the boys, since females have two dark spots on their forewing, males only one.

You would have no way of knowing this, but the wings of the female reflect ultraviolet light (male wings don’t). This may give her a day-glow radiance in the eyes of potential mates, and actually isn’t an uncommon sex characteristic among our butterfly friends. It makes me wish I hadn’t given away my black light way back when.

The cabbage white is not only the most common butterfly in New Jersey, but one of the most successful colonizers in the insect world. Native to Europe, northwest Africa and Asia, they were introduced accidentally to Canada in 1860. From there, they made their inexorable way southwestward, conquering California by 1883, Hawaii by 1893, New Zealand by 1930 and Australia by 1943. Not bad for a little bug.

Cabbage white caterpillar. — Matt from London/Creative Commons

The rapid spread is partly due to the cabbage white’s love of big families, their adaptability and the fact that they are on the move from the last frost of spring to the first frost of fall. In between, as many as three generations can ravage your cabbage patch as larvae and suck up to your nectar-bearing flowers as adults.

As the name implies, cabbage is a preferred larval food, and each successive generation in a given season does progressively more damage, devouring leaves and burrowing into the heart of maturing cabbage heads. They like peppery foliage, apparently, feeding on plants in the Cruciferae family, including nasturtiums, mustard, radishes, turnips.

In captivity, caterpillars of the cabbage white so favor the mustard oils present in these plants that they would rather starve than eat some bland old substitute. The oils may give them some measure of protection against predation, although few individuals live more than five weeks before getting gobbled up by birds, toads and mantises or succumbing to disease.

Since I am not intentionally growing plants on the preferred food list, I’m hoping that the horde of caterpillars preceding my own bumper crop of butterflies is busily eating the garlic mustard, an evil weed that competes with nutsedge for top billing on my list of public enemies. They can eat it all, as far as I’m concerned.

This brings us to one of life’s true facts: You can’t have the butterfly without the caterpillar. When people report a virtual absence of butterflies in their gardens, it’s usually because they are spraying pesticides. One potent butterfly quasher is Bt, a bacteria non-toxic to humans and most beneficial insects, but deadly to caterpillars.

If it’s food crops you’re after, go for the Bt. You can also try pairing your cabbage with lavender as a repellent or planting some hyssop, coriander or wormwood nearby to lure the pests away. Crushed eggshells around the cabbages or cauliflower might fool a butterfly mom into believing that eggs providing competition to hers are already present.

But as in so many cases in life, you may have to decide between two mutually exclusive choices. Is it the cabbage you want, or the cabbage whites? The cole slaw, or the butterflies?