|Lady Beetle Larva, Pupa - Harmonia axyridis|
Family Coccinellidae - Lady Beetles. These beetles and their larvae are beneficial to agriculture and the backyard gardener, being voracious predators of aphids, thrips, flies and mites.
Lady Beetle Larva attacks a root-maggot fly
The multicolored Asian ladybug was imported in an early attempt at biological control of aphids; it has naturalized rapidly and inhabits most of North America. Ditto the so-called 7-Spotted lady beetle. It just shows the succes of the beetle body-plan in exploiting the ubiquity of that predator-prey ratio: aphids and their ilk are extremely prolific reproducers; their predators are therefore many and varied. It all boils down to a complex web of interactions beginning with animals capable of exploiting plants' ability to make sugar from sunlight.
Ladybugs often overwinter as adults in gregarious swarms under fallen leaves, bark, or inside unheated buildings. As insects go, they are a very beneficial group, being natural enemies of many insects, especially aphids and other critters that damage plants by feeding on their sap. A single ladybug can consume vast quantities of aphids in its lifetime, perhaps as many as 5,000 or more. During the Middle Ages, these beetles were used to control aphid infestations of grapevines in vinyards.
Aphids in the suborder Homoptera are plant sap-processing machines. They feed by inserting their hypodermic needlelike proboscis directly into a plant's vascular system (phloem), which contains carbohydrate laden sap, under pressure. As a passive but very efficient process, sap flows into the insect's digestive system. (Other predatory species inflict essentially the same process on their prey, except instead of sap, they are vacuuming out the victim's liquefied innards.)
Coleomegilla maculata larva feeding on flower pollen
Adult ladybugs have convex, hemispherical shaped elytra (the hardened wings used to cover the soft flying wings underneath) that can be yellow, pink, orange, red, or black, and usually are marked with distinct spots. This is a type of warning coloration (aposematic coloring), thought to discourage predators. Lady beetles also have another defense: an odorous, noxious fluid that seeps out of their leg joints when the insects are disturbed.
Ladybugs, both adults and larvae, are well-known primarily as predators of aphids (plant lice), but they prey also on many other pests such as soft-scale insects, mealybugs, spider mites and eggs of the Colorado Potato Beetle and European Corn Borer. A few feed on plant and pollen mildews. One larva will eat about 400 medium-size aphids during its development to the pupal stage. An adult will eat about 300 medium-size aphids before it lays eggs. About three to ten aphids are eaten for each egg the beetle lays. More than 5,000 aphids may be eaten by a single adult in its lifetime. The lady beetle's huge appetite and reproductive capacity often allow it to rapidly clean out its prey.
Ladybug pupa, Harmonia axyridis. Note red mite hitchhiker
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Order Coleoptera: Beetles are the dominant form of life on earth: one of every five living species is a beetle. Coleoptera is the largest order in the animal kingdom, containing a third of all insect species. There are about 400,000 known species worldwide, ~30,000 of which live in North America. Beetles live in nearly every habitat, and for every kind of food, there's probably a beetle species that eats it.
Beetles Index | Longhorns | Leaf Beetles | Soldier | Blister | Lady | Scarab