Lady beetles, commonly recognized as ladybugs or ladybirds, are familiar insects found in gardens and various landscapes across the globe. These small, dome-shaped beetles, often adorned with vibrant colors and spots, are a common sight. Over 450 species exist in North America alone, including native and introduced varieties. Their presence in agricultural settings and home gardens is largely due to their beneficial behaviors.
Their Primary Food Sources
Most lady beetle species are predatory, primarily consuming soft-bodied insects that damage plants. Aphids are the most significant food source for many varieties. These tiny, slow-moving insects extract sap from plants, making them a common agricultural pest.
Lady beetles effectively control aphid populations, making them beneficial insects in gardens and farms. An adult lady beetle can consume up to 50 aphids per day, with some species consuming several hundred. Their larval stage is also voracious; a single larva can devour approximately 400 aphids over three weeks.
Lady beetles actively hunt for aphids, and their ability to rapidly reduce aphid numbers makes them valuable for natural pest control. Once an aphid colony is depleted, they seek additional food sources.
Other Dietary Habits
Beyond aphids, lady beetles consume other soft-bodied insects and arthropods, especially when primary prey is scarce. Their diet includes scale insects, mealybugs, mites, thrips, and whiteflies. Some species also prey on insect eggs, such as those of moths and other beetles, or small caterpillars and leaf beetle larvae.
This adaptability allows lady beetles to sustain themselves when aphid populations are low. Adult lady beetles, particularly omnivorous species, also supplement their insectivorous diet with plant-based foods. These include pollen and nectar, which provide essential carbohydrates and nutrients.
Pollen offers proteins, fats, vitamins, and minerals, supporting their nutritional needs and reproductive health. Some lady beetles also feed on honeydew, a sugary excretion from aphids, or fungal spores like powdery mildew. Overripe fruit can serve as a supplementary food source for certain species, providing quick energy.
How Diet Changes Through Life Stages
The diet of lady beetles varies across their life stages: egg, larva, pupa, and adult. Eggs are typically laid near a food source, ensuring newly hatched larvae have immediate access to prey.
Larvae are carnivorous, consuming many soft-bodied insects like aphids to fuel rapid growth. For instance, a single larva of the multicolored Asian lady beetle can consume up to 370 aphids during its development. After several weeks of feeding and molting, the larva transforms into a pupa, a non-feeding stage where it undergoes metamorphosis.
As adults, lady beetles continue to feed on insect pests. However, adult lady beetles, particularly some species, also incorporate non-prey foods like pollen and nectar into their diet. These plant-derived resources are important for adult survival and reproduction, especially for overwintering species. Diverse flowering plants can support adult lady beetle populations by providing these supplementary food sources.