1.  Lady Beetles
Lady beetles, also called ladybugs and ladybird beetles, are beneficial insects that prey mostly on aphids, but also eat scales, mealybugs, and mites. They belong to the large insect family Coccinellidae, which means scarlet red. People often think of lady beetles as red with black spots, but there are many different species that range in color from gray and black to bright orange. The larvae are flat, orange or gray, alligator-shaped insects, with legs on the front half of the body. Unlike the adults, they have no wings or wing covers. The cigar-shaped eggs are usually orange, and stand upright in clusters of a dozen or more. A single lady beetle may lay up to 1,500 eggs during her life. The larvae that hatch from the eggs feed on aphids or other insects, devouring up to 25 aphids a day. Because lady beetles are such voracious eaters, they require high populations of aphids to maintain themselves. Adults may eat 50 or more aphids a day. If the prey population is reduced to such low numbers that there are not enough aphids on which to feed, the lady beetles will migrate or starve to death. The aphid population will gradually rebuild, possibly followed by a return of the lady beetle population. These population fluctuations are very common between predators and their prey. Lady beetles can be purchased at garden stores or through mail-order houses. These insects have been collected from huge masses in areas where they hibernate. When they are placed out in the garden, there is no guarantee they will stay. Even when there is food available, lady beetles often have an urge to migrate. Some may remain in the garden, but most will move to your neighbors' yards.