Lady beetle

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Coccinella septempunctata (seven-spotted)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Superfamily: Cucujoidea
Family: Coccinellidae
Coccinella transversalis, elytra (wing cases) in the open position
Harmonia axyrdis, the harlequin ladybug, has many colour varieties
For the sports comedy movie, see Ladybugs

Lady beetles are of the Coccinellidae: a family of beetles. All species are protected by noxious fluids based on cyanide [citation needed], and most have warning colouration [citation needed], such as red with black spots.

They are often called 'lady bugs' or 'ladybirds', but biologists prefer the term 'coccinellid' or 'lady beetle' [citation needed].

Coccinellids are found worldwide, with over 5,000 species.[1] Most species are insectvorous, feeding mainly on the true bugs, the Hemiptera [citation needed]. These 'true bugs' are insects which feed on plants, such as aphids (greenfly) or scale insects. Ladybeetle larvae are also voracious (greedy) eaters of greenfly, and aphids.

As Biological Control[change | change source]

Harmonia axyridis (or harlequin ladybug [beetle?]) was introduced into North America from Asia in 1988 to control aphids [citation needed]. It is now the most common species in North America, out-competing many of the native species[2]. It has since spread to much of western Europe, reaching the UK in 2004[2][3].

Defence[change | change source]

A lot of Coccinellids are brightly coloured to warn potential predators citation needed]. This phenomenon is called aposematism. It works because predators learn by experience to associate certain prey phenotypes (appearance) with a bad taste (or worse)[citation needed].

Mechanical stimulation (such as a predator attack) causes "reflex bleeding" in both larval and adult ladybird beetles [citation needed]. A toxin is put through the joints of the exoskeleton, deterring feeding. This method works well: birds and cats seldom try twice[citation needed].

Appearance[change | change source]

[[File:Coccinellidae (Ladybug [beetle]) Anatomy.svg|thumb|right|250px|alt=A diagram of the ladybug and its body parts|]]

A ladybeetle's pronotum may sometimes be mistaken for the ladybug's whole head [citation needed]. Most people know lady beetles as small, round, red beetles with black spots on their backs[citation needed]. In Europe, the most common lady beetle is seven-spotted Coccinella septempunctata[citation needed].

Not all lady beetles are red; and not all red lady beetles have spots, some are plain black. For example, some lady beetles are very small, black and hairy[citation needed]. Lady beetles vary in color. For example, red, orange, or yellow with black spots, again, they can be black with red spots. It is also worth pointing out that some are missing spots altogether and as such are a solid colour, e.g., black. What is more, there are a few kinds of ladybeetles coloured with metallic blue iridescence, and some have checkerboard markings or stripes [citation needed].

The (usually) black front part (pronotum) of the ladybeetle is the thorax and the head[citation needed].

Life and food supply[change | change source]

Ladybeetle larvae
Ladybeetle larvae look like strange adult insects

Most coccinellids overwinter as adults.[4] In Harmonia axyridis, eggs hatch in 3–4 days from clutches numbering from a few to several dozen. Depending on the supply of aphids, the larvae pass through four instars over 10–14 days, after which pupation occurs. After several days, the adults become reproductively active and are able to reproduce again, though not late in the season. Total life span is 1–2 years on average.

It only takes about four weeks for the ladybeetle to transform from a tiny egg to an adult. Some females can lay up to 1,000 eggs in one summer. The ladybeetle may lay her eggs near an aphid colony, or on plants where the larvae will have a ready supply of food when they hatch.

Almost all lady beetles are insectivores: they eat other insects. Many of these insects have soft bodies, such as aphids. Even the larvae eat other insects. Aphids are a huge problem for farmers and gardeners, and therefore a ladybug is a great help to the farmer. Some species of ant herd aphids like sheep, and will attack a ladybeetle that tries to eat one of their aphids.

References[change | change source]

  1. Judy Allen & Tudor Humphries 2000. Are you a ladybug?, Kingfisher, p30.
  2. 2.0 2.1 Anon (5 October 2004). "'Deadly ladybird' sighted in UK". BBC News. BBC. Retrieved 17 June 2010. 
  3. Anon. "The Harlequin Ladybird has landed!". The harlequin ladybird survey. Retrieved 17 June 2010. 
  4. A. Honek, Z. Martinkova & S. Pekar (2007). "Aggregation characteristics of three species of Coccinellidae (Coleoptera) at hibernation sites". European Journal of Entomology 104 (1): 51–56.