Harlequin ladybird (Harmonia axyridis)

Also known as: Asian ladybird beetle, Asian multicoloured ladybird, Halloween beetle, Halloween lady beetle, Halloween ladybird, Halloween ladybug, Japanese lady beetle, multicolored Asian lady beetle, multicoloured Asian ladybird, multicoloured Asian ladybird beetle, multicoloured ladybird, pumpkin ladybird
KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderColeoptera
FamilyCoccinellidae
GenusHarmonia (1)
SizeAdult length: 5 - 8 mm (2) (3)
Top facts

The harlequin ladybird has yet to be classified by the IUCN.

A brightly coloured beetle with a highly variable appearance, the harlequin ladybird (Harmonia axyridis) is an invasive species which has spread rapidly outside of its native range (2) (3) (4) (5) (6). Its common name comes from the chequered pattern of some individuals of this species (4).

Like other ladybirds, the harlequin ladybird is rounded in shape and has hard, colourful forewings, or ‘elytra’, which cover the abdomen. Its legs are short and can be retracted beneath the body, and its antennae are short and have clubbed ends. A structure between the head and elytra, known as the pronotum, is wider than it is long, and the ladybird’s head can be retracted beneath it (3) (4).

The harlequin ladybird is well known for its very variable colouration and patterning. The background colour of its elytra can vary from pale yellow-orange to orange, red or black, and the orange and red forms may be unspotted or have up to 21 black spots or a grid-like black pattern (3) (4). Black forms of this species usually have two or four large orange or red spots (3) (4), although individuals with bars, stripes or large patches of a pale colour also occur (3).

The lower surface of the harlequin ladybird’s body is usually yellow-orange to black, while its head may be black, yellow, or black with yellow markings (3) (5). This species’ pronotum is usually creamy-yellow or white with black markings in the form of four to five black spots, two curved lines, an M-shaped mark or a solid black trapezoid (3) (4) (5), and each side of the pronotum has a yellow, oval-shaped spot (5). The harlequin ladybird’s legs are almost always brown (4).

In total, over 100 different colour variations of the harlequin ladybird have been identified worldwide, with the different forms varying between locations and sometimes between seasons (3). Many subspecies have been described (5), and the harlequin ladybird’s great variation has led to the species’ alternative name of ‘multicoloured ladybird’ (4). Although the colour patterns in this species are largely controlled by its genes, they can also be influenced by the diet of the larvae and the temperature at which the pupae develop (3) (5).

The larva of the harlequin ladybird is quite different in appearance to the adult, being grub-like, around two to ten millimetres in length, and covered in branched spines. Its body is largely black, but in older larvae each side of the body bears an orange, ‘L’ shaped mark, and there are four orange spines towards the rear (3) (5) (7).

Harlequin ladybird pupae are ‘exposed’, meaning that the entire larval skin is shed during pupation, rather than the ladybird pupating within it or only half shedding it. The cast-off larval skin remains attached to the rear of the pupa, at the point where the pupa attaches to a substrate while it develops (3) (5).

The harlequin ladybird is native to eastern Asia, where it occurs from central Siberia, the Altai Mountains and the Himalayas east to China, Mongolia, Japan and the Korean Peninsula (2) (3) (4) (5) (6).

Widely introduced outside of its native range as a biological control agent, the harlequin ladybird has spread rapidly across many areas. It has now invaded North America, much of Europe and several South American countries, as well as Tunisia, Egypt and South Africa (2) (3) (4) (5) (6) (7). In North America, this insect is now the most widespread ladybird species (4) (7).

A number of harlequin ladybirds have been intercepted arriving in Australia by air (3) (6), and both Australia and New Zealand remain at risk of invasion by this successful insect (6).

An adaptable species, the harlequin ladybird inhabits a wide variety of habitats, from urban and agricultural areas to woodland, wetlands and meadows (2) (3) (4) (6). It can also survive in a range of climates (3). This species commonly lives on trees, particularly fruit trees, which support large populations of its aphid prey (2) (3) (6).

The harlequin ladybird’s ability to exploit a diverse range of habitats may be one factor in its success at spreading across new areas (3).

The harlequin ladybird is a voracious aphid predator. Harlequin ladybird larvae can consume as many as 90 to 370 aphids during their larval period, while adults typically eat up to 65 a day (3) (5), equating to over 5,000 in their adult lifetime (3). Females usually eat more aphids than males (5). In addition to aphids, the harlequin ladybird also eats a range of other insects, including scale insects, the eggs and larvae of butterflies and moths, and even other ladybirds. Pollen, nectar, fruit juices and honeydew are also consumed (4) (5).

The bright colours of this and other ladybirds serve to warn potential predators that they are distasteful. If attacked, the harlequin ladybird secretes a yellowish substance known as ‘reflex blood’, which contains distasteful toxins and smells unpleasant. However, despite these defences, harlequin ladybirds may be predated by some birds, spiders, predatory insects and even bats, and their eggs and larvae may be eaten by other ladybirds (3) (4) (5) (7) (8). This species is also parasitised by the larvae of some wasps and flies (2) (3) (4) (7) (8). The harlequin ladybird can be cannibalistic, eating members of its own species when other prey is scarce, but individuals appear to recognise their close relatives and are less likely to cannibalise a sibling than a non-sibling (3) (5).

As in other ladybirds, the life cycle of the harlequin ladybird involves an egg, larval, pupal and adult stage (3) (4) (5). Each female harlequin ladybird can produce around 1,000 to 2,000 or so eggs in its lifetime (4) (5) (9) (10), usually laying them in batches of about 10 to 30 per day (5) (9). The eggs of this species are oval-shaped and are pale yellow when laid, later turning darker yellow before becoming grey-black just before hatching (3) (5).

The time taken for the harlequin ladybird’s eggs and larvae to develop depends on a number of factors, including temperature and diet. In temperate regions, the eggs usually hatch after around four to five days and the larvae take about three weeks to develop (2) (3), shedding their skins four times during this period (4) (7). The harlequin ladybird’s pupal stage lasts about one week (2) (3) (4).

In its introduced range in the United Kingdom, the harlequin ladybird is reported to lay the majority of its eggs in June and July, with the adults emerging from the pupae in August (7). After feeding on plenty of aphids to see them through the winter months (4), the adults of this species spend the winter in a dormant state, often overwintering in large aggregations in dark, concealed locations, including buildings (2) (3) (4) (5) (7). Harlequin ladybirds usually migrate to their overwintering sites from around September to November (3) (5). As this period coincides with Halloween, this species is also sometimes known as the ‘Halloween ladybird’ in the United States (4) (5).

As temperatures warm up in the spring, the adult harlequin ladybirds become active again and leave their overwintering sites to search for food and to mate (3) (4) (5) (7). The adult harlequin ladybird usually lives for about a year, and is reproductively active for around three months of this (2) (3). Unlike many other ladybird species, which require a period of winter dormancy before they can breed and have only one generation each year, the harlequin ladybird often has two generations in a year (2) (3) (5). In some areas with longer warm seasons, it may even have as many as four or five generations (3) (5).

There are not known to be any major threats to the harlequin ladybird in its native range. This species is adaptable and successful, and has become established in many areas outside of its natural range, where it has spread rapidly and is considered to be invasive. The harlequin ladybird was introduced deliberately in many regions as a biological control agent to control populations of aphids and other pest insects (2) (3) (6). It can also spread to new areas on imported flowers, fruit and vegetables and in vehicles and trains (2) (3) (4) (6), and some are thought to have reached the United Kingdom by flying across the English Channel (2) (4).

Outside of its natural range, the harlequin ladybird is thought to pose a threat to other ladybird species, both by outcompeting and directly predating them (2) (3) (4) (5). This species has a number of advantages over other ladybirds, including its large size, broad diet, tolerance of a wide range of habitats and climate conditions, long reproductive period and high reproductive rate (3) (4) (5). In some areas, the harlequin ladybird also has a higher winter survival rate than native ladybird species (11). Declines in native ladybird species in the United Kingdom and United States have been directly attributed to this invasive species (3) (12).

When aphids are scarce, the harlequin ladybird readily switches to other prey species, which may potentially have negative effects on non-pest insects, such as butterflies (5). It may also compete for food with insects other than ladybirds (2).

As well as affecting other species in its non-native range, the harlequin ladybird can cause problems for humans. For example, it can become a nuisance where it aggregates in large numbers inside buildings in winter, and it may occasionally bite, which can cause an allergic reaction in a small number of cases. The harlequin ladybird can also damage fruit crops by feeding on the fruits in autumn, when aphids become scarce (2) (3) (4) (5). This species is regarded as a pest in vineyards, as it is difficult to remove it from grapes during processing and its distasteful toxins can taint the wine (3) (4) (5).

No conservation measures are currently targeted at this widespread invasive species. In the United Kingdom, the UK Ladybird Survey is monitoring the spread of the harlequin ladybird and its impacts on native ladybird species, and encourages the public to report sightings (4) (7).

Suggested methods to deter harlequin ladybirds from entering houses include sealing holes or using insecticides or deterrents at entry points (3) (5). Recommendations have also been made for vineyard cultivation practices that reduce the impact of this beetle on wine production. To try and prevent or reduce further spread of the harlequin ladybird, imported fruit and flowers should be checked to ensure they are not harbouring any stowaways (3), and more research should be done into the species’ natural enemies and their potential for helping to control this invasive species (3).

Although various negative impacts are predicted as the harlequin ladybird continues to expand its non-native range (6), this species does have benefits as an effective means of controlling aphids and other pest insects, and this in turn reduces the use of insecticides on crops (3) (5) (6).

Find out more about the harlequin ladybird:

More information on recording UK ladybirds:

Authenticated (11/10/13) by Richard Comont, entomologist, the UK Ladybird Survey. Blog:
http://insectrambles.blogspot.co.uk/

  1. Integrated Taxonomic Information System (ITIS) (September, 2013)
    http://www.itis.gov/
  2. GB Non-native Species Secretariat (NNSS): Factsheet - Harlequin ladybird (September, 2013)
    https://secure.fera.defra.gov.uk/nonnativespecies/factsheet/factsheet.cfm?speciesId=1668
  3. Invasive Species Compendium: Datasheets - Harmonia axyridis (harlequin ladybird) (September, 2013)
    http://www.cabi.org/isc/?compid=5&dsid=26515&page=481&site=144
  4. The Harlequin Ladybird Survey (September, 2013)
    http://www.harlequin-survey.org/
  5. Koch, R.L. (2003) The multicolored Asian lady beetle, Harmonia axyridis: A review of its biology, uses in biological control, and non-target impacts. Journal of Insect Science, 3(32): 1-16.
  6. Brown, P.M.J., Thomas, C.E., Lombaert, E., Jeffries, D.L., Estoup, A. and Lawson Handley, L.-J. (2011) The global spread of Harmonia axyridis (Coleoptera: Coccinellidae): distribution, dispersal and routes of invasion. BioControl, 56: 623-641.
  7. UK Ladybird Survey (September, 2013)
    http://www.ladybird-survey.org/
  8. Comont, R. (October, 2013) Pers. comm.
  9. Stathas, G.J., Eliopoulos, P.A., Kontodimas, D.C. and Giannopapas, J. (2001) Parameters of reproductive activity in females of Harmonia axyridis (Coleoptera: Coccinellidae). European Journal of Entomology, 98: 547-549.
  10. Wang, H., Ji, S. and Zhai, W. (2009) Effect of temperature on survival, development and fecundity of Harmonia axyridis. Chinese Bulletin of Entomology, 46(3): 449-452.
  11. Raak-van den Berg, C.L., Stam, J.M., de Jong, P.W., Hemerik, L. and van Lenteren, J.C. (2012) Winter survival of Harmonia axyridis in The Netherlands. Biological Control, 60(1): 68-76.
  12. Roy, H.E. et al. (2012) Invasive alien predator causes rapid declines of native European ladybirds. Diversity and Distributions, 18(7): 717-725.