AppearanceThe adult 24-spot is a small ladybird, usually 3 to 4 mm long. It has the quintessential ladybird shape, quite domed with the sides forming a smooth curve from head to pronotum to wing-cases. The wing-cases are covered with short pale hairs, and though these are hard to see without a hand lens, they give the ladybird a distinctive matt appearance. The ladybird is dark orange, including legs and antennae. There are black spots on the wing cases. These vary in number and size but there are often about 20 to 24 and usually no more than 26. Sometimes spots are joined together or they can be absent completely. Dark forms are very rare. Another extremely rare form has yellow spots.
Larvae are 4 to 6mm long and pale grey-green with darker speckles. They are covered with branched spines. These spines are also present in the pupa, enabling the pupa to secrete noxious alkaloids as a defence against predators.
There are five European species in the Epilachninae subfamily, all herbivorous and somewhat hairy. The 24-spot Ladybird can be distinguished from the similarly patterned Bryony Ladybird - ''Henosepilachna argus'' by its small size . ''Cynegetis impunctata'', another small ladybird, is browner and has no spots. It also has a black head and this separates it from the form of the 24-spot Ladybird without spots.
This ladybird usually has no wings under the elytra and these individuals are unable to fly. A study found no winged specimens in a UK sample whereas 40% of those from Hungary and Romania had wings. However, as even the winged specimens carried the gene that causes atrophy, it is thought that winglessness is a trend that will increase.
NamingThe common names for this insect in many languages follow the binomial name and mention that it has twenty-four spots, but in English there is great variation in how this is written, with little consensus over the use of words or numerals, capitalisation, placement of hyphens and whether to use "spot", "spotted", "point" or "pointed"; "ladybird", "ladybird beetle" or "ladybug". There is even disagreement about the spelling of the Latin "''vigintiquatuorpunctata''" with some authoritative UK lists preferring a double "t": "''vigintiquattuopunctata''". For ease it is often written "''Subcoccinella 24-punctata''". Given the multitude of name formations, it is probably best to use just the genus "''Subcoccinella''" when carrying out a web search for information about this insect to avoid missing texts that use variant spellings - it's the only species in the genus. In the US it is also known as the "Alfalfa Lady Beetle", though rarely found on alfalfa in North America.
DistributionThis ladybird is an Old World species occurring across Europe. It ranges south into parts of north Africa and eastwards through northern Asia excluding China. It was introduced into North America some time last century with the first records from Pennsylvania in 1972. In Britain it is more common in the south.
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