In spring, a young butterfly’s fancy turns north

VIC LEIPZIG AND LOU MURRAY

For some species in the animal kingdom, spring means that it’s time

to migrate. That was certainly the case over the weekend for painted

lady butterflies.

Vic and I were leading clients from South Africa on a bird-finding

foray when we happened across a massive migration of these gorgeous

butterflies in the Lake Elsinore area Friday. Clouds of butterflies

drifted past us while we searched the sage scrub for sparrows, and

scanned the sky for migrating sifts and swallows. Friends who had

visited Anza Borrego over the weekend weekend reported a similar

sight, with butterflies on every bush.

Painted lady butterflies are dark orange on the topside with black

spots on the hind wings and white patches on a black background on

the forewings. The wing underside is actually my favorite view of

this butterfly. They have pink-orange patches on the underside of the

forewings, with black and blue eyespots on the hind wings. Vic likes

their antennae, which are black with large white knobs at the ends.

The butterfly migration lasted all weekend, with reports of large

numbers throughout inland Orange County, particularly Mission Viejo,

Lake Forest, Brea and Orange. The butterflies had come from their

wintering grounds in the deserts of northern Mexico.

In spring, they head north. The butterflies that pass through our

region will travel all the way to Oregon. Other populations fan out

from northern Mexico through Texas and Arizona to head to other parts

of the United States.

To get from northern Mexico to the northern United States and

southern Canada, the butterflies migrate 1,500 miles or farther.

The butterflies live two to four weeks, and can fly about 100

miles on a warm, sunny day. If it’s raining or cold, they hunker down

and wait for better weather. It seems amazing, but these little

insects theoretically could travel that long migration route from

Mexico to Oregon in about two weeks.

But these butterflies do more than just fly. They stop to feed,

mate and lay eggs along the migratory pathway. While they feed by

sipping nectar from flowers, the butterflies perform an important

role in the ecosystem. They are pollinating the flowers that they

feed upon. They also provide food for birds, amphibians, reptiles and

small mammals as some fall prey along the way.

In the afternoons, male butterflies will cease migrating long

enough to perch on a high shrub to search for females that are ready

to mate. The female signals that she is receptive with airborne

chemicals called pheromones. The male hones in on the signal, and

nature takes its course. The female then lays about 500 tiny,

blue-green eggs on suitable host plants.

Some of the butterflies that flew through last weekend undoubtedly

laid eggs throughout our region. In about three to five days, the

eggs will hatch into caterpillars, which will feed on their favored

plants of thistles, mallows, and legumes, mostly in open fields or

desert scrub. The caterpillars feed on their host plant for 12 to 18

days, shedding their skin five times as they grow larger. When

they’re ready, they form a pupa, or chrysalis.

Inside the casing, the little caterpillar undergoes a remarkable

transformation. In a complex biochemical process of tissue

degradation and reformation, it transforms in about 10 days from a

yucky, bristle-covered, creepy-crawly into a delicate, winged

creature of amazing grace and beauty.

The newly hatched butterfly will pump fluid into its damp, folded

wings. When the wings are fully expanded and have stiffened and

dried, the butterfly will take off and continue along the migration

route. The result is that waves of painted ladies migrate through as

each new population hatches and continues the migration. There may be

several waves that pass through our area between February and April.

Somehow, the butterflies know whether they’re supposed to be

flying north or south. No one butterfly ever makes the full

south-to-north migration from Mexico to the northern U.S. and back

again. It’s truly a wonder of nature how these creatures are able to

carry out a complex migration that spans multiple generations.

But even a species as abundant as painted ladies has its ups and

downs. Some years, they are the most numerous butterflies around, and

some years they are scarce. When conditions are right in their

wintering range, such as this year, we get great clouds of them

passing through. Other peak migrations were reported in our area in

2001 and 2004. Last year, the migration caused a slowdown on the San

Diego Freeway as a dense river of butterflies attempted to fly

through 12 lanes of traffic. Millions of butterflies failed in their

migratory quest when they hit windshields and radiators with gooey

splats.

Painted ladies are found on every continent except Australia and

Antarctica. One of the reasons for their widespread distribution is

that painted lady caterpillars aren’t fussy eaters. They have been

observed feeding on over a hundred different kinds of plants. That

may help explain why this is one of the world’s most numerous and

widely distributed butterflies.

Another reason for their abundance is that they particularly like

living in vegetated, disturbed areas. Where there are humans, there

are plenty of disturbed areas. It’s nice that something in nature

benefits from our human activity and that their abundance reflects

our own.

We hope that you got to witness this migratory rite of spring

wherever you were last weekend.

* VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and

environmentalists. They can be reached at [email protected].