Coccinellidae (Ladybug) is a family of beetles, known variously as ladybirds (English English, Australian English, South African English) ladybugs (North American English) or lady beetles (preferred by scientists). The word "lady" in the name is thought to allude to the Virgin Mary in the Roman Catholic faith. The family name comes from its type genus, Coccinella. Coccinellids are found worldwide, with over 5,000 species described, more than 450 native to North America alone. Coccinellids are small insects, ranging from 1 mm to 10 mm (0.04 to 0.4 inches), and are commonly yellow, orange, or scarlet with small black spots on their wing covers, with black legs, head and antennae. A very large number of species are mostly or entirely black, gray, or brown, however, and may be difficult for non-entomologists to recognize as coccinellids (and, conversely, there are many small beetles that are easily mistaken as such, like tortoise beetles).
They are considered useful insects as many species feed on aphids or scale insects, which are pests in gardens, agricultural fields, orchards, and similar places. Because they are useful, colourful, and harmless to humans, coccinellids are typically considered appealing even by people who hate most insects, though a few species are pests in North America and Europe. Some people consider seeing them or having them land on one's body to be a sign of good luck to come, and that killing them presages bad luck.
Coccinellids (Ladybugs) are typically predators on Hemiptera such as aphids and scale insects, though members of the subfamily Epilachninae are herbivores, and can be very destructive agricultural pests (e.g., the Mexican bean beetle). They are also known to eat certain plants and crops when no other food is present, making them a possible pest to farmers and gardeners. While they are often used as biological control agents, introduced species of ladybugs (such as Harmonia axyridis or Coccinella septempunctata in North America) can outcompete and displace native coccinellids, and become pests in their own right.
Coccinellids (Ladybugs) are often brightly colored to ward away potential predators. This defense works because most predators associate bright colours (especially orange and black or yellow and black) with poison and other unpleasant properties. This phenomenon is called aposematism. In fact, most coccinellids are indeed poisonous to smaller predators, such as lizards and small birds; however, a human would have to eat several hundred coccinellids before feeling any effects. Adult coccinellids are able to reflex-bleed hemolymph from their leg joints, releasing their oily yellow toxin with a strong repellent smell. This becomes quite obvious when one handles a coccinellid roughly.
Most Coccinellids (Ladybugs) mate in the spring or summer, and the female lays a cluster of eggs (numbering from a few to a few hundred, depending on species) as near as possible to an aphid colony. In most species these eggs hatch into a larval state within a week. This state lasts 10–15 days, and they then go into a pupal stage before becoming an adult coccinellid. The entire life cycle of the Coccinellid is only 4–7 weeks. Most ladybird species are univoltine, producing only one generation a year, although some are bivoltine.
Coccinellids (Ladybugs) lay extra infertile eggs with the fertile eggs. These appear to provide a backup food source for the larvae when they hatch. The ratio of infertile to fertile eggs increases with scarcity of food at the time of egg laying.
Some species are migratory and form large aggregations during the migratory period. They also form large aggregations when they go into hibernation in winter.
Most ladybugs are beneficial to gardeners in general. In the
spring, one could usually find a ladybug in a vegetable garden
feeding on aphids. As in many insects, ladybugs in temperate
regions enter diapause during the winter. Some species (e.g.,
Hippodamia convergens) gather into groups and move to higher
land, such as a mountain, to enter diapause. Ladybugs are
usually found where aphids or scale insects are, and they lay
their eggs near their prey, to increase the likelihood the
larvae will find the prey easily. Since aphids and scale insects
occur nearly everywhere in the world, ladybugs are also
Although native species of ladybugs are typically considered benign, in North America the Asian lady beetle (Harmonia axyridis), introduced in the twentieth century to control aphids on agricultural crops, has become a serious household pest in some regions owing to its habit of overwintering in structures. It is similarly acquiring a pest reputation in Europe, where it is called the "Harlequin Ladybird" (see main article "Asian lady beetle" for discussion).
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