Beetles represent a diverse order of insects, Coleoptera, encompassing hundreds of thousands of identified species globally. Their diets vary significantly across this group, ranging from plant material and fungi to other insects and decaying organic matter. This dietary flexibility allows beetles to inhabit nearly every ecosystem on Earth, excluding only the open sea and polar regions. Given their wide-ranging feeding habits, it is reasonable to consider whether certain beetle species consume grass, a common plant found in many environments.
Beetles That Consume Grass
Several types of beetles feed on grass, particularly during their larval stage, known as grubs. These grubs cause significant damage to turf by consuming grass roots. Examples include the Japanese beetle, various scarab beetles (like June bugs), European chafers, and billbugs.
Japanese beetle and European chafer grubs primarily feed on turfgrass roots, leading to browning and eventual death. Billbug larvae target plant crowns and roots. While adult Japanese beetles feed on leaves, flowers, and fruits, their grubs are the primary threat to grass roots.
Most grubs are white, C-shaped larvae with three pairs of legs near their heads. They reside just below the soil surface, feeding on root systems and weakening the grass. Billbug larvae are legless, creamy, and have brown heads, distinguishing them from other white grubs.
Identifying Beetle-Related Grass Damage
Beetle infestations in lawns often manifest through several signs. One common indicator is irregular brown or dead patches of grass. These patches can start small and expand as grubs continue to feed on grass roots. The grass in damaged areas may also feel spongy or loose underfoot due to the compromised root system.
A clear sign of grub damage is grass that can be easily pulled up from the soil, often described as rolling back like a carpet. This occurs because grubs have severed the roots anchoring the grass. Another sign of a grub infestation is the presence of animals like skunks, raccoons, and birds digging in the lawn. These animals are attracted to grubs as a food source, and their digging can further damage the turf. While a few grubs are normal, finding more than five to ten grubs per square foot can indicate a problem.
Understanding Beetle Feeding Habits
The feeding habits of grass-eating beetles are tied to their life cycle, which involves four stages: egg, larva, pupa, and adult. Adult beetles, after emerging, focus on mating and laying eggs, often in lawn soil. These eggs hatch into grubs.
Environmental conditions play a role in the presence and activity of these beetles. Grubs thrive in moist soil conditions, and adult beetles prefer to lay eggs in areas with abundant organic material. Damage from grubs is most severe in late summer and fall as the larvae mature and actively feed.