Pest Lexicon – Green Guardia

Garden Chafer: Identifying and naturally containing beetles & grubs

The garden chafer often goes unnoticed until the lawn suddenly looks limp: The larvae (grubs) feed on the roots and can undermine entire areas. Adult beetles can also nibble on leaves – but the greater damage occurs in the soil. With the right beneficial organism, the infestation can be reduced very effectively and naturally.

ⓘPhyllopertha horticola · Garden chafer #Grubs · Lawn root feeding · Bare patches

What is the garden chafer?

The garden chafer (Phyllopertha horticola) is a small scarab beetle that flies as an adult in early summer/summer. The females lay eggs in the soil (often in lawns). From these, grubs hatch, which feed on plant and lawn grass roots. As a result, patches of grass loosen easily and turn yellow to brown.

Beetles in summer Larvae in soil Lawn roots affected

Important: Grubs of different beetles look similar. To choose the right measure, it is important to confirm whether grubs are truly in the soil (and not, for example, suffering from drought stress or fungal problems). A simple test: lift a piece of lawn – if the roots loosen easily and you find larvae, that is a strong indication.

How to identify an infestation

yellow to brown patches in the lawn that spread
grass sod can be peeled off like a carpet (roots are missing)
grubs in the soil (C-shaped, whitish)
increased bird activity/wildlife signs in the lawn (they are looking for larvae)
adult beetles in summer on leaves/grasses

Green Guardia Tip: Check the lawn at the edges of the damaged area: larvae are often present in higher density there. A spade cut is usually enough to get clarity.

Which areas are frequently affected?

Lawns (especially sunny/warm locations)
Beds with grasses and perennials (root feeding possible)
Gardens with sandy, loose soil

Why does an infestation occur?

warm weather favors flight and egg-laying
loose, rather dry soils are attractive
lawn is weakened (drought stress, poor maintenance)
few natural antagonists in the soil

Natural measures & the right beneficial organism

1. Strengthen the lawn (prevention)

water regularly during dry spells (deeply instead of "a little every day")
aerate/scarify the lawn (not too aggressively)
soil improvement measures (humus, sand depending on soil type)

Beneficial organism recommendation: Nematodes against grubs

Nematodes are the right natural solution for grubs in the soil (depending on the larva species, e.g., Heterorhabditis or Steinernema species). They are active in the soil and help to reduce the larvae.

Why appropriate: Larvae live in the soil – nematodes work exactly in this habitat.
Why sensible: They reduce grubs before root damage becomes widespread.
Important: Soil must be sufficiently moist; application is best at suitable temperatures.

Why this recommendation fits: The main damage is caused by grubs feeding on roots. Nematodes target the area where mechanical measures barely reach – directly in the soil.

FAQ about the garden chafer

Is every grub in the lawn a garden chafer?

No. Other beetle species also have grubs. The decisive factor is the combination of damage pattern, finding them in the soil, and potentially the beetle's flight time. For practical purposes, what counts is: reduce grubs if they are damaging the roots.

When is the best time for nematodes?

When young larvae are active and the soil is warm enough – often summer to early autumn. Good soil moisture before and after application is important.

Why are birds tearing up my lawn?

Birds (and sometimes other animals) are searching for grubs. This is a strong indication of larvae in the soil.

Can the lawn recover?

Yes – if the grubs are reduced and the lawn is well-maintained afterward, damaged areas often fill in again.