Lawn pests, including chafer grubs, play a significant role in garden and lawn ecosystems, often causing damage to grass roots and creating unsightly lawns. Understanding their life cycle is key to managing and mitigating their impact effectively. Let’s discuss the life cycle of chafer grubs as a primary example of lawn pests.
Laying Period: Adult chafer beetles lay eggs in the soil during late spring to early summer.
Location: Eggs are typically laid a few inches below the soil surface, often in lawns or areas with rich soil.
Hatching: Eggs hatch into larvae within a few weeks, depending on the species and environmental conditions.
Appearance: The larvae are creamy white grubs with a distinct C-shaped body, brown heads, and six legs near the head.
Feeding: Chafer grubs feed on the roots of grasses and other plants, causing significant damage to lawns and turf.
Duration: They can spend one to three years in the larval stage, growing larger and molting several times.
3. Pupa (Spring)
Transformation: After fully developing, the larva transitions into a pupa. This stage occurs in the soil, usually 10-15 cm below the surface.
Time Frame: The pupal stage lasts for several weeks. During this time, the grub metamorphoses into an adult beetle.
Emergence: Adult chafer beetles emerge from the soil in late spring to early summer, starting the cycle anew.
Activity: After emerging, adults mate and lay eggs within a few weeks. They are most active during the evening hours.
Lifespan: Adult beetles have a relatively short lifespan, living for a few weeks to a couple of months, during which they feed on foliage.
Crows, along with other birds such as magpies, rooks, and starlings, are known to feed on chafer grubs. They are most active in their search for these grubs during the periods when the grubs are closest to the soil surface and more abundant. This typically occurs in two main periods during the chafer grub’s life cycle:
Late Summer to Early Autumn: After the eggs laid by adult chafer beetles hatch, the young grubs are active near the surface of the soil. During this time, they are feeding on grass roots, which makes them easier for crows and other birds to find and eat. The moist soil conditions of late summer and early autumn facilitate the birds’ ability to dig into the soil and extract the grubs.
Spring: As the soil warms up in spring, the overwintering grubs (which may have moved deeper into the soil to escape the colder temperatures) become more active again and move closer to the surface to continue feeding before pupating. This increased activity near the surface makes them vulnerable to predation by crows.