The family Scarabaeidae, commonly known as scarab beetles, contains over 35,000 species globally. These beetles exhibit varied dietary preferences that reflect their ecological roles, from agricultural pests to environmental recyclers. Scarabs consume nearly every type of organic material, including living plant tissue, animal waste, rotting wood, fungi, and carrion. A scarab’s diet depends entirely on its specific species and its stage in the life cycle.
Feeding Habits of Larvae and Adults
Scarab nutrition differs significantly between the larval and adult life stages. The larval stage, often called a grub, is the primary feeding period, consuming large quantities of food for growth. These C-shaped larvae live hidden underground or within a food source.
Adult scarabs emerge primarily to reproduce, and their feeding habits are inconsistent. Some, like the Japanese beetle, are voracious feeders on foliage, while others feed lightly on leaves or tree sap. Some adult species, particularly dung beetles, may not feed at all, relying solely on energy reserves stored during the larval phase.
Scarabs That Eat Living Plants
Many scarab species feed on living plant material, making them common garden or lawn pests. This behavior is split between subterranean larvae that target roots and adult beetles that consume above-ground foliage, flowers, and fruit. For example, the larvae of June beetles, known as white grubs, live in the soil and feed on the roots of grasses and ornamental plants.
Grub feeding is highly destructive, particularly during the third instar when larvae are largest and require the most sustenance. High populations cause root destruction, leading turf to turn brown in irregular patches. A damaged lawn can often be rolled back like a carpet because the roots are severed. Adult scarabs, such as the Japanese beetle, target the aerial parts of plants. These adults are known for “skeletonizing” leaves by consuming the soft tissue between the veins, leaving a lace-like pattern.
Scarabs That Consume Decaying Matter
Other scarabs consume non-living organic matter. This diverse group includes saprophages, which feed on decaying plant material, and coprophages, which specialize in animal feces. Dung beetles are the most recognizable coprophages, classified as rollers, tunnelers, or dwellers based on how they process the waste.
Adult dung beetles feed on the liquid nutrients and microorganisms within the dung. Their larvae consume the solid dung, often packed into a protective brood ball by their parents. Other scarabs consume different types of decay; for example, rhinoceros and Hercules beetle larvae feed on rotting wood. Other species consume fungi, decaying fruits, and leaf litter, recycling nutrients back into the ecosystem.