Insects on smaller scale common problem

By Gary Raham
Correspondent

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March may have its blustery faults, but it does bring the glimmerings of spring. Greenhouses beckon with moist, warm smells and lush greenery --previews of growing delights we can't wait to see again.

If you are a salad fan, like me, every tomato seedling holds the promise of ripe, red, juicy, homegrown globes that will--in a few short months --replace the pale, orange, cardboard, almost-tomatoes offered in grocery stores.

Sometimes, other creatures find greenhouses inviting, too, and may hitch a ride on that plant you couldn't resist buying. If this hadn't happened to me one spring, I probably would never have learned of the bizarre life of scale insects.

This particular year my cucumbers swelled to green tastiness and melon vines crept everywhere. But my tomatoes languished. They grew slowly, sticking out narrow leaves that curled upward and looked half wilted even after healthy rainstorms. Prospects for those much-anticipated July and August salads looked grim.

Brownish specks and a fine, white powder salt-and-peppered the surface of these withered leaves. I suspected some kind of fungus, but plucked a few leaves and retreated to my basement where I could magnify the enemy and take his measure. I found bugs--true bugs in the biological sense --because they were insects in the order Homoptera. Like cicadas, leafhoppers and aphids, these homopterans practiced a leaf-sucking lifestyle, but they were very tiny and quite un-insect like. Under magnification, I saw something approximately 1/16-inch long, shaped like a thin, convex lens or tiny, Chinese peasant hat. They moved very little, but if flipped over, quickly righted themselves. They possessed stubs where wings should be, and the green of my tomato plant's leaves glowed in their innards. My insect keys proclaimed them to be terrapin scales because of their turtle-like appearance.

I entered this miniature world for some time, watching these turtle-shaped armored tanks (brown specks) and their white boulder eggs (white powder) that littered the green carpet of my pathetic tomato leaves. The leaf edges curled upon themselves, creating cozy tunnels that I'm sure shielded the insects from their usual enemies. Many species, I learned, have winged males who disdain eating for the serious business of reproduction. Mature females may lose legs and antennae completely, becoming nothing more than egg factories and immobile, wax-covered, reinforced shelters. Newly hatched larvae disperse the species by crawling off to new territory or catching a warm, summer breeze to tomato plants far far away.

Most scale insects, my books assured me, weren't serious pests, but the species I had discovered is a common problem in greenhouses. Other scale insects attack citrus fruit crops. On the positive side, Asian scale insects produce waxes or "lacs" that become shellacs, lacquers, varnishes and the red dye, carmine. For the most part, however, their 6,000 known species live their lives beneath notice, mostly in green terrains tucked away in tropical or temperate forests.

Another scale insect, commonly called the mealybug, also enjoys greenhouse living. Mealybugs look like segmented, oval lozenges covered with cottony threads of wax. Sometimes, on plants like cactus, India-rubber plant or philodendron, you can wash them off with a strong stream of water. They also succumb to touching them with a brush or cotton swab dipped in alcohol - if their numbers are not too great to handle with the personal touch. For the scale insects that attach more tightly to plants, various light-oil-emulsion insecticides may be effective.

My scale insects resisted the sprays I tried, so my salads that August didn't have much red to color them. I ate lots of cucumbers, green peppers and melons, though, and I've got memories of a tiny world I wasn't aware of before. I guess that's an even trade.