Our Window on Nature

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Bugs for Sale

Filed under: Bugs — Lowell Christie -- January 15, 2007 @ 9:44 am

LadybugsA rose by any other name looks better without aphids. And eating aphids is the specialty of the ladybird beetle, affectionately known as the ladybug. The ladybug earned its nickname by devouring pests that have been tormenting man ever since the Garden of Eden.

Back in the Middle Ages (and before the Age of Insecticides), these beetles appeared just in time to gobble the bugs infesting Italian vineyards, leading farmers to christen them “The Beetles of Our Lady.” That name caught on (except in France, where they’re considered “The Cows of the Lord” of all things.) Englishmen call them ladybird beetles.

We’re in error when we shorten the name to ladybug, for at least in a technical sense, these insects aren’t bugs, but beetles. But at least the name is a short one, more appropriate for their diminutive size.

Several species of ladybugs exist in this country, their names being descriptive of the patterns of lines on their heads and number of spots on their bodies. Most of the insects possess bright red-orange wings, yet in the Southwest you find some ladybird beetles colored a stylish celadon green. Elsewhere, species wear yellow wings marked with black spots. Still others have their colors reversed — orange or yellow or green spots on shiny black backs.

Today’s gardener cares less about a ladybug’s aesthetic value than about its appetite. They wish these critters would devote less of their time to sleeping and more of it to chasing down aphids in the cabbage patch. The convergent ladybird beetle, for example, slumbers away as much as three-quarters of the year.

Elsewhere in the country, ladybugs are content to overwinter in cracks in buildings or beneath bark and leaves, but in the West the convergent ladybird beetle heads for the high country. By early June, after only a few months of high living in garden and field, the western edition of these tiny orange and black insects is already in search of winter quarters.

Birds, marine mammals and other kinds of migrants may hang around until it starts to get cold before heading south to escape the snow and ice, but these ladybugs dance to the beat of a different drummer. They summer and winter in the mountains. Watch for them when you drive or hike to the top of a tall peak. We’ve paused breathless after climbing that last few feet, only to discover that we’re far from alone. Ladybugs surrounded us — by the hundreds — thousands.

Up in the high country where aphids are few, ladybugs switch to a diet of pollen. Like certain other insects, a female ladybug is programmed by what she eats. While still in the low country, when aphids are on the menu, she lays eggs. Once she substitutes pollen, however, the ladybug ceases egglaying and begins storing fat to sustain her over a nine-month period of dormancy.

During these cold winter months convergent ladybugs of both sexes gather in dense masses, like bright orange cankers or cancerous growths. Clear up on top where the wind blows strongest, they’ll cluster into every crack and cranny they can find, totally cover tree trunks, spread across the ground. As many as 30 million ladybugs can squeeze into a quarter-acre of mountaintop.

There’s a reason why ladybugs settle into winter quarters in such open, wind-swept areas — that’s where spring arrives first. By late February and March, melting snow brings life back into this mountaintop insect world. The ladybugs stir, indulge in a brief mating season, and then fly back down to the valleys.

Wings flickering at more than 75 beats a second carry millions of ladybugs to backyard gardens and farmers’ fields — wherever the supply of aphids is abundant. Fortunately, ladybugs consume astronomical numbers of these unlovely insects. Each female eats about 100 aphids before she settles down to producing and attaching her lemonyellow eggs to the underside of leaves. Naturally she selects the most aphid-infested territory she can find; yet by the time her life cycle ends in May, she faces stiff competition on the food front, for the larvae from her 400 eggs are out there devouring aphids on their own. Her progeny may consume more than 100,000 aphids before reaching adulthood.

After about five days, ladybug eggs hatch into larvae, ugly bristly creatures that share the same coloration as their parents but none of their charm. Be that as it may, these youngsters devour the same prey they later eat as adults. And they do it practically nonstop for three solid weeks, until it’s time to pupate. Achieving adult status doesn’t lessen their appetite either. Right up until that bell chimes signaling them to migrate, this new group of ladybugs eats from morning to dark.

Since ladybugs don’t time their schedules to man’s demands, researchers have studied ways to prolong the ladybug’s year. Best known perhaps are the bug collectors who climb up to the mountaintop wintering grounds and bring down sacks full of dormant ladybugs. They store them at near-freezing temperatures until aphid-removal services are needed; then they sell them by the gallon to farmers and gardeners.

At 75,000 ladybugs to the gallon, it should be easy to cure your aphid problem. But a ladybug’s migratory instincts are exceedingly strong, and when that inner clock says move — off they go. You may have paid for their services, but they didn’t sign the contract. That’s why you lose about 90 percent of your ladybugs to the neighbors. Or to the mountains.

FMC1285


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