ladybird beetle

ladybird beetle or ladybug, member of a cosmopolitan beetle family with over 4,000 species, including 350 species in the United States. Ladybird beetles are mostly under 1/4 in. (6 mm) long and are nearly hemispherical in shape, with very short legs. They are usually red or yellow with black spots, or black with red or yellow spots, the common species differing only in the number of spots. They have a bitter taste, and their bright coloration is thought to serve as a warning to predators. The name is believed to date from the Middle Ages, when these beneficial beetles were dedicated to the Virgin. Nearly all ladybird beetles, both larvae and adults, are predators on destructive, plant-eating insects. The eggs are laid on plants infested with aphids or scale insects, on which the larvae feed until they pupate in the remains of the last larval skin. The adults gather in large numbers in the fall, prior to winter hibernation, and are often collected at that time by farmers for use in pest control. The first outstanding demonstration of pest control by use of natural enemies occurred in the United States in 1889, when Australian ladybird beetles (Rhodolia cardinalis) were imported to wipe out the cottony-cushion scale, an insect that had accidentally been imported from Australia to California and there became a threat to citrus orchards. The Mexican bean beetle (Epilachna varivestis), which has spread through E North America, and the squash beetle (E. borealis) are the only North American ladybird beetles considered destructive. They are yellowish with black spots; adults and larvae feed on plants. Ladybird beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Coccinellidae.

or ladybird beetle

Any of the approximately 5,000 widely distributed beetles of the family Coccinellidae. The name originated in the Middle Ages, when the beetle was dedicated to the Virgin Mary and called “beetle of Our Lady.” Ladybugs are hemispheric and are usually 0.3–0.4 in. (8–10 mm) long. They have short legs and are usually brightly coloured with black, yellow, or reddish markings. Several generations are produced each summer. Ladybugs are often used to control such insect pests as aphids, scales, and mites, which they eat. Several species of ladybugs feed on plants.

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The two-spotted lady beetle (Adalia bipunctata) is a carnivorous beetle of the family Coccinellidae and is very common in western Europe. It is used as a biological control agent against aphids, e.g. in greenhouses.

The most familiar form of the two-spot ladybird beetle is the red one with the two black spots. However, there also exists a black form with red spots on it. In addition, there are intermediate forms, but they occur only rarely in nature. The two-spotted lady beetle's life cycle starts with eggs that are usually laid in clutches. The larvae hatches from the egg by biting a hole in it. The larvae look very different from the adults: they have elongated, grey, soft bodies with six legs but no wings. They are cannibalistic. Larvae go through four larval stages: by eating they grow and at some point they shed their old skin and appear in a new one in which they can grow more. The last larval stage is approximately the size of an adult beetle. Once it has eaten enough, the larvae attach themselves to a substrate and moult into a pupa. Inside the pupa, the adult develops. Finally the adult encloses from the pupa.

In some populations, the majority of the beetles are female. In these populations, 80-90% of the offspring of a females are female. The cause of this anomaly is the presence of a symbiotic bacteria living within the gametic cells of the female lady beetles. The bacteria is too large to live in the male gametes (sperm), so the bacteria can be transmitted to the next generation only through female gametes. When it ends up in a male, it will die when the male dies. Therefore, it kills most of the male embryos in the newly-laid eggs. These dead embryos then serve as food for their sisters when they emerge from their eggs. This trait is associated with a variety of different bacteria (Wolbachia, Rickettsia, Spiroplasma), which are present in between 0 and 20% of females, depending on locality.

The two spot ladybird also carries a sexually transmitted infection in Central and Eastern Europe. The infection is an ectoparasitic mite that transfers between male and female (and female and male) during copulation. The infection sterilizes female two spot ladybirds, and at some points of the year, up to 90% of adult 2-spots become infected.

External links

• http://www.enature.com/fieldguides/detail.asp?recnum=IS0016
• http://www.discoverlife.org/20/q?search=Adalia+bipunctata
• http://animaldiversity.ummz.umich.edu/site/accounts/information/Adalia_bipunctata.html