Convergent Lady Beetle

Hippodamia convergens — the convergent lady beetle — is the native North American ladybug and one of the most ecologically important beneficial insects on the continent. The species is widespread across all of North America from southern Canada through Mexico, and is one of about 6,000 species in family Coccinellidae (the lady beetles). Adults are 4-7 mm long, dome-shaped, with bright orange-red wing covers bearing typically 13 black spots (variable from 0 to 13 across populations). The species' identifying feature is the pair of CONVERGING WHITE LINES on the pronotum (the segment behind the head) — these distinguish the convergent lady beetle from the European seven-spot ladybird, the multicolored Asian lady beetle, and other ladybug species in North America. The species is the FOREMOST commercially-collected biocontrol agent in North America. Every spring, hundreds of millions of overwintering adult beetles are collected from massive aggregations in the Sierra Nevada Mountains of California (and to a lesser extent the Rocky Mountains), refrigerated to keep them in dormancy, packaged, and shipped to gardeners and small-scale farmers across the continent for release as aphid biocontrol. The collection industry is a major California seasonal business and operates with state oversight to prevent over-harvesting. The OVERWINTERING AGGREGATION BEHAVIOR is one of the most spectacular insect mass events in the western US: millions of convergent lady beetles fly to high-elevation sites in late summer and cluster together in tight bowls of vegetation (especially in shaded canyons and on rocky slopes near snowmelt), forming visible orange-red mats covering hectares of mountain slope. The aggregation persists from autumn through spring, with the beetles entering dormancy and surviving on stored body fat through the cold months. The aggregation behavior is thought to provide thermal protection and overwintering humidity. Adults and larvae are equally voracious aphid predators — each beetle consumes 50+ aphids per day during active feeding, and a single larva consumes 200-400 aphids during its development. The species is one of the most beneficial natural-control agents of aphid pests in North American agriculture.