Ladybugs, or ladybirds as they are also called, are neither bugs nor birds. Entomologists prefer the name lady beetle, which accurately places these lovable insects in the order Coleoptera. Whatever you call them, these well-known insects belong to the family Coccinellidae.
Ladybugs share a characteristic shape – a dome-shaped back and a flat underside. Ladybug elytra display bold colors and markings, usually red, orange, or yellow with black spots. People often believe the number of spots on a ladybug tells its age, but this is not true. The markings may indicate a species of Coccinellid, although even individuals within a species can vary greatly.
Ladybugs walk on short legs, which tuck away under the body. Their short antennae form a slight club at the end. The ladybug's head is almost hidden beneath a large pronotum. Ladybug mouthparts are modified for chewing.
Coccinellids became known as ladybirds during the Middle Ages. The term "lady" references the Virgin Mary, who was often depicted in a red cloak. The 7-spot ladybird (Coccinella 7-punctata) is said to represent the Virgin's seven joys and seven sorrows.
Most ladybugs are predators with ravenous appetites for aphids and other soft-bodied insects. Adult ladybugs will eat several hundred aphids before mating and laying eggs on the infested plants. Ladybug larvae feed on aphids as well. Some ladybug species prefer other pests, like mites, white flies, or scale insects. A few even feed on fungus or mildew. One small subfamily of ladybugs (Epilachninae) includes leaf-eating beetles like the Mexican bean beetle. A small number of beetles in this group are pests, but by far the majority of ladybugs are beneficial predators of pest insects.
Ladybugs undergo complete metamorphosis in four stages: egg, larva, pupa, and adult. Depending on the species, female ladybugs may lay up to 1,000 eggs within a few months from spring to early summer. Eggs hatch within four days.
Ladybug larvae resemble tiny alligators, with elongated bodies and bumpy skin. Most species go through four larval instars. The larva attaches itself to a leaf, and pupates. Ladybug pupae are usually orange. Within 3 to 12 days, the adult emerges, ready to mate and feed.
Most ladybugs overwinter as adults. They form aggregates, or clusters, and take shelter in leaf litter, under bark, or other protected places. Some species, like the Asian multicolored lady beetle, prefer to spend the winter hidden in the walls of buildings.
Special Adaptations and Defenses:
When threatened, ladybugs "reflex bleed," releasing hemolymph form their leg joints. The yellow hemolymph is both toxic and foul-smelling, and effectively deters predators. The ladybug's bright colors, red and black in particular, may signal its toxicity to predators as well.
Some evidence suggests that ladybugs lay infertile eggs along with fertile ones, in order to provide a food source for hatching larvae. When the natural food supply is limited, the ladybug lays a higher percentage of infertile eggs.
Range and Distribution:
The cosmopolitan ladybug can be found throughout the world. Over 450 species of ladybugs live in North America, though not all are native to the continent. Worldwide, scientists have described over 5,000 Coccinellid species.