xture of food and poison in infested areas. This seemed to solve the problem. However, today these bait trays do not seem to work as well (5:27). This is not because cockroaches have become resistant to the poison, according to Jules Silverman and Donald N. Bieman, entomologists at the Clorox Technical Center in Pleasanton, California. It is because cockroaches have evolved a dislike of the bait's glucose.
Silverman and Bieman discovered that the insect had lost its taste for sweets after they collected German cockroaches from apartments where the bait had ceased to be effective. They evaluated each bait component by comparing the responses of these apartment insects with those of insects reared in the laboratory with no prior history of exposure to the bait trays. While the poison killed both groups, the apartment cockroaches, after touching the glucose with their antennae, backed away from the poison (5:27).
This glucose aversion showed up in apartment cockroach populations from California to Florida, and the researchers suspect that such mutants exist throughout the cockroach world. Since these mutants avoided bait trays, they survived while the sugar-loving cockroaches did not -- and eventually an aversion to sugar became common. Fortunately, cockroaches do not seem to be adverse to other kinds of sugars.
Another way scientists have tried to control insect populations has been to import other insects to act as predators. The ladybug or ladybird beetle is one such insect. A wide-ranging species, these predators live in a variety of habitats. In Arizona's lowlands, ladybird larvae hatch at the end of spring and feed on aphids for a month before they pupate and become young adults (4:74).
In most years, aphids become scarce as the field grow dry and hot, and the newly matured ladybirds fly miles toward the mountains where they will feed on pollen. Afterward, they gather in dense aggregations on mountain sum...