Ladybug, or ladybird beetles, are recognizable insects known for their bright colors and spotted markings. The vast majority of the over 6,000 species worldwide are carnivorous, making them highly effective natural predators. Their specialized diet focuses on controlling agricultural pests, which makes them valued allies in horticulture and farming.
The Primary Predatory Diet
The diet of most ladybug species centers on soft-bodied, slow-moving insects, primarily aphids. Aphids are an ideal food source because they are abundant and found in dense, immobile colonies, making them easy targets for both adult and larval ladybugs. A single adult ladybug can consume 50 to 100 aphids per day, potentially eating up to 5,000 in its lifetime.
Ladybugs are major biological control agents, as their menu extends beyond aphids to include other common agricultural pests. They readily feed on scale insects, mealybugs, spider mites, thrips, whiteflies, and the eggs and larvae of various other insects. By efficiently suppressing pest populations, their presence reduces the need for chemical pesticides.
Supplemental and Survival Foods
Ladybugs are opportunistic feeders and supplement their carnivorous diet with plant-based resources. These non-prey foods help sustain them when insect prey is scarce. Nectar and pollen are important components, especially for adult beetles, providing essential carbohydrates and proteins that support metabolic and reproductive health.
Adult ladybugs also consume honeydew, a sugary residue excreted by sap-sucking pests like aphids. This substance provides a quick source of energy and attracts ladybugs to areas with high pest density. Some species also feed on fungal spores and mildew on plant leaves, demonstrating dietary flexibility.
Dietary Differences Across the Life Cycle
The ladybug’s diet changes significantly across its four life stages. The larval stage is characterized by a large appetite; larvae are small and resemble tiny alligators. A single larva can consume 350 to 400 aphids during its two to four-week development period before pupating.
Female ladybugs strategically lay eggs near aphid colonies to ensure young have immediate access to food upon hatching. If prey is scarce, newly hatched larvae may resort to cannibalism, consuming unhatched eggs or weaker siblings for protein. Adult ladybugs require less food than the rapidly growing larvae and rely on supplemental foods to fuel flight and reproduction.
The Few Vegetarian Species
Not all ladybugs are beneficial, as a small minority of species are phytophagous, meaning they feed exclusively on plants. These exceptions belong mainly to the subfamily Epilachninae, which constitutes less than 10% of the total ladybug population. The Mexican bean beetle (Epilachna varivestis) is a notable example; both its larvae and adults chew holes in the leaves of bean plants and other legumes, causing crop damage.
The squash beetle (Epilachna borealis) is another herbivorous species that feeds on the foliage of cucurbits like squash and pumpkins. These plant-eating species are distinct from their predatory relatives and are correctly classified as agricultural pests.