Forest Preserve District of Cook County, Illinois
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Nature Bulletin No. 82   September 7, 1946
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Supt. of conservation

Gardeners have remarked this summer upon the unusual number of lady-bugs. This was largely due to the great quantity of aphids or plant- lice last year. Like all other animals, insects have enemies which normally tend to limit their numbers if man does not upset things. These enemies may be diseases, mites, reptiles, rodents, birds or other insects. As an insect becomes abundant its enemies, too, tend to become more numerous. These soon deplete their food supply and themselves decline in numbers, after which their prey increases again. And so it goes, in cycles.

There are large numbers of insects of different kinds which prey on other insects. Cone group consists of parasites that live within or on a single "host" and gradually consume it. The other group surprises the predators which, as adults or larvae or both, kill and eat large numbers of their prey. Among the most beneficial of the predator insects are the "lady-bugs" or ladybird beetles: known to children because of the Old Mother Goose rhyme; praised and protected by the vegetable gardener, the farmer, the fruit grower and the forester.

The adults of the many species that feed, both as larvae and as adults, on aphids are nearly hemispherical in shape, about 1/4 inch or less in diameter, with reddish or yellowish wing-covers decorated with black spots, or black wing-covers with white, red or yellow spots. The number, size, location and color of the spots distinguish the species. They hibernate during the winter in protected places, emerging in spring to lay their eggs. The larvae are active strange-looking creatures, many of them mottled with bright colors and covered with warts or spines, always fiercely hungry.

The two plant-eating exceptions, the bean lady-bug and the squash lady- bug are destructive pests. Those that feed on scale-insects are smaller, flatter an shiny black some of them having red or orange spots. These were introduced from Australia as a means of combating the San Jose and other scales. Most of our native species prey on the aphids that infect melons, cucumbers, squash, pumpkins, corn fruit trees or forest trees.

The male lady-bug is called just that.

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