Subcoccinella

Distinguished from other small ladybirds by the combination of small size (3–4 mm), domed shape, velvety hair-covered elytra, and orange coloration with black spots. The Bryony Ladybird (Henosepilachna argus) is larger (6–8 mm) with similar patterning. Cynegetis impunctata is browner, spotless, and has a black head—unlike the spotless form of Subcoccinella, which retains an orange head. The hairy, matt elytra separate it from smooth, shiny aphid-feeding ladybirds.

Adults are small ladybirds, 3–4 mm in length, with a domed, semi-spherical body shape. The elytra (wing-cases) are covered with short pale hairs, giving a distinctive matt or velvety appearance rather than the smooth, shiny surface seen in most ladybirds. Coloration is dark orange, including legs and antennae, with variable black spots on the elytra—typically 20–24, occasionally up to 26, sometimes fewer or absent, and occasionally fused together. Melanic (dark) forms are very rare; an extremely rare form has yellow spots. Many adults are wingless, with no wings under the elytra. Larvae are 4–6 mm long, pale grey-green with darker speckles, and covered with branched spines. Pupae retain these spines, which are used in chemical defense.

Occurs in diverse habitats including Pontic–Caspian steppe, Pannonian steppe, unimproved grassland, quarries, wasteland, ruderal areas, broadleaf and mixed forests, and riparian zones. In Britain, more common in southern and coastal regions. Adults frequently found on flowers, especially Apiaceae.

Native to the Palearctic: Europe, North Africa, European Russia, the Caucasus, Siberia, Russian Far East, Belarus, Ukraine, Moldova, Transcaucasia, Kazakhstan, Middle Asia, Western Asia, Afghanistan, Mongolia, China, and North and South Korea. Introduced to North America, first recorded in Pennsylvania in 1972. In Britain, predominantly southern distribution.

Adults active from late spring through autumn. Eggs laid in May. Larval development approximately six weeks. New generation adults active until October or November. Adults enter reproductive diapause at the end of July, remaining active until late autumn. Overwintering adults experience high mortality and die during May–June.

Herbivorous. Larvae feed on mycelium of powdery mildew fungi (Erysiphales), primarily Podosphaera species on oak (Quercus robur) and ash (Fraxinus excelsior), as well as on grasses, Astragalus, and some Fabaceae and Boraginaceae. Adults feed on leaves of herbaceous plants including grasses, campions, plantains, and legumes. Insects carry fungal spores.

• Quercus robur - fungal host plantlarvae feed on Podosphaera mildew on oak
• Fraxinus excelsior - fungal host plantlarvae feed on Podosphaera mildew on ash
• Poaceae - fungal host plantlarvae feed on mildew fungi on grasses
• Astragalus - fungal host plantlarvae feed on mildew fungi
• Fabaceae - fungal host plantlarvae feed on mildew fungi on some species
• Boraginaceae - fungal host plantlarvae feed on mildew fungi on some species
• Podosphaera - food sourcepowdery mildew fungi consumed by larvae
• Erysiphales - food sourceorder of powdery mildew fungi consumed by larvae

Eggs laid in May on vegetation. Larval development through four instars, taking approximately six weeks. Pupation occurs on vegetation. Adults emerge from late June onwards. New generation adults active until October or November. Reproductive diapause induced by interaction of photoperiod and temperature, beginning end of July. Overwintering as adults in sheltered locations; hibernation unstable with high mortality. Overwintering adults die during May–June. Cool temperate climate limits population size. Some adults may become active during mild winter periods due to year-round food availability.

High proportion of adults wingless in some populations (no UK winged specimens found in one study; 40% winged in Hungary and Romania), limiting dispersal. Winged individuals also carry genes for wing atrophy, suggesting increasing trend toward flightlessness. Chemical defense via alkaloid secretion used as ant deterrent; formerly thought to lack alkaloids. Conspicuous aposematic coloration. Larvae and pupae use branched spines to secrete noxious alkaloids against predators.

Herbivore feeding on plant leaves and fungal mycelium. Contributes to fungal spore dispersal through carrying spores. Not regarded as a significant plant pest in Britain due to climate limiting population size, though capable of damaging alfalfa and other legumes in parts of its range. One of only two herbivorous ladybird species resident in the UK.

Known as the "Alfalfa Lady Beetle" in the United States, though rarely found on alfalfa in North America. Can cause damage to alfalfa and legume crops in some regions. Subject of genome sequencing as part of the Darwin Tree of Life project. Common name variability creates search challenges—numerous spellings and formats exist for the species epithet.

• Henosepilachna argusSimilar spot pattern but larger (6–8 mm vs. 3–4 mm) and smoother elytra
• Cynegetis impunctataSimilar small size but browner, completely spotless, and has black head (spotless Subcoccinella retains orange head)

Widely assumed to be predatory like most ladybirds, but exclusively herbivorous. Formerly thought to lack the alkaloid chemical defenses typical of ladybirds, but now known to produce alkaloids used against ants. The name "Alfalfa Lady Beetle" in North America is misleading as the species is rarely found on alfalfa there.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Observations on the biology of Subcoccinella vigintiquattuor‐punctata (L.) in southern England
• The genome sequence of the 24-spot ladybird, Subcoccinella vigintiquattuorpunctata (Linnaeus, 1758) (Coleoptera: Coccinellidae).