White grubs are the larvae of several kinds of scarab beetle, and they are one of the most common reasons a lawn suddenly develops brown patches that lift like a carpet. You may never see the adult beetles — many of them fly at night and feed quietly — but the grubs are hard to miss once you lift a piece of turf: fat, C-shaped, creamy white, with a brown head and three pairs of legs, curled in the soil just below the surface. In garden beds they chew the roots of seedlings and young plants, which wilt and pull up easily.
This guide explains how to identify white grubs, tell them apart from wireworms, understand the damage they cause, and control them with organic-first methods in order. If you are not sure the grubs in your soil are white grubs, the pest identifier helper can help you compare, and our Japanese beetles guide covers the best-known species in detail.
How to identify white grubs
A white grub is the larva of a scarab beetle — Japanese beetles, June beetles, chafers and others all have similar-looking grubs. It is plump and C-shaped, creamy white with a brown head capsule and three pairs of legs near the head, usually 20–40 mm long when fully grown. The body is soft and slightly translucent, and the rear end is often darker because of the soil in the gut. When disturbed, a grub curls tighter into its C shape.
White grubs are often confused with wireworms, but the difference is clear once you see them side by side: wireworms are thin, straight, hard-bodied and yellow-brown, while white grubs are fat, curved, soft and creamy white. The two need different controls, so it is worth getting the identification right. If you are unsure, take a photo and check your local extension service — many regions have a dominant grub species, and the local advice will be specific to it.
The adults vary by species: Japanese beetles are metallic green and copper and feed in the day, June beetles are large and brown and fly at night, and chafers are smaller and brown. The grubs of all of them do similar damage.
Lifecycle in general terms
Most white grub species have a one-year lifecycle, though some take two or three years. The adults emerge in late spring or summer, mate and lay eggs in the soil, usually in lawns and grassy ground. The eggs hatch into small grubs that feed on grass roots through late summer and autumn, then burrow deeper to overwinter. In spring they return toward the surface and feed again before pupating in late spring or early summer, and the adults emerge to start the cycle again.
Because the whole cycle runs through the lawn, grub numbers in a bed are usually highest where the bed is near a lawn, and they are worst in late summer and early autumn, when the grubs are large and feeding hard. The timing matters: controls aimed at young grubs in late summer work far better than controls aimed at large grubs in spring.
Damage signs
The classic sign is the lawn: irregular brown patches that feel spongy underfoot, and turf that lifts easily like a carpet because the roots have been eaten away. Birds, skunks and raccoons may tear at the lawn to reach the grubs, and that digging often causes more visible damage than the grubs themselves. In garden beds, grubs feed on the roots of seedlings, young transplants and soft-rooted plants, which wilt, yellow and pull up easily with few roots left.
A few grubs are normal in any lawn — healthy turf tolerates them, and the soil life includes predators that eat them. The problem starts when numbers rise above roughly six to ten grubs per square foot, though the threshold varies with grass type, soil and season. If you grow potatoes or lettuce near a lawn, check the roots of any plant that wilts for no obvious reason.
Grub damage is sometimes confused with drought, fungal disease or dog damage. The test is simple: lift a square of turf in the brown patch and look in the soil underneath. If you find C-shaped white grubs, you have your answer.
Organic-first control, in order
1. Inspect first. Lift a square foot of turf in a few places — in the brown patches and in healthy grass for comparison — and count the grubs in the top few centimetres of soil. Do this in late summer, when the grubs are young and near the surface. This count tells you whether treatment is needed at all, and it gives you a baseline to compare against next year.
2. Hand-pick and remove. When you dig a bed, pick out any grubs you find by hand and put them out for the birds — a tray of grubs on the lawn is quickly cleared by robins and starlings. In a small lawn, lifting turf and hand-picking is practical; in a large one, it is not, and the steps below matter more.
3. Barriers. There is no practical barrier against a pest that lives in the soil, but you can protect vulnerable plants. Grow seedlings and transplants in pots until they are sturdy, and plant them out with a good root system that can tolerate some feeding. In beds near a lawn, a deep edging can reduce grub movement, though it will not stop it entirely.
4. Traps. There are no effective traps for grubs in the soil, and light traps for the adults catch only a small proportion of the population. Do not spend money on traps for this pest — the effort is better spent on the steps below. Monitoring with turf samples, as described above, is the useful form of "trapping" here.
5. Beneficial organisms. Beneficial nematodes are the best-known biological control for white grubs. They are microscopic worms that enter the grub and kill it, and they work best when applied in late summer to young grubs, in moist soil and warm conditions. Results vary with species, soil type and timing, so follow the label carefully and check your local extension service for the right species for your region. Milky spore disease is another biological option, specific to Japanese beetle grubs, which can persist in the soil for years once established but takes a season or more to build up. Encourage birds by providing water and shelter, and avoid broad-spectrum sprays that kill the ground beetles and other predators that eat grubs.
6. Least-toxic options last. Neem-based products applied to the lawn can deter egg-laying and may affect young grubs, but results are variable and they need reapplying. Avoid broad-spectrum lawn insecticides: they kill the predators and soil life that keep grub numbers in check, and they can make the problem worse the following year. If grub numbers are very high and the lawn is badly damaged, the honest answer is often to repair the lawn and build up biological control over time, rather than to spray.
Prevention
A healthy lawn is the best prevention. Water deeply and infrequently so the roots grow deep, mow at a higher setting so the grass shades the soil, and overseed bare patches in autumn so there is less open ground for egg-laying. Avoid overwatering in midsummer, when females are choosing where to lay eggs — moist soil attracts them. Keep the lawn fed so it can tolerate some root feeding, and avoid scalping it in hot weather. In the vegetable garden, rotate crops and avoid planting the most vulnerable seedlings in beds right next to a heavily infested lawn. Digging and cultivating the soil exposes grubs to birds and to drying out, and a well-drained, biologically active soil supports the predators that eat them. Check the planting calendar for zone 6 in September for autumn overseeding times in your area.
Frequently asked questions
How many grubs are too many? A few per square foot is normal and harmless. Problems usually start above six to ten per square foot, though the threshold varies with grass type and season. Count before you treat, and check your local extension service for the threshold in your area.
Are white grubs and wireworms the same thing? No. White grubs are fat, C-shaped and creamy white; wireworms are thin, straight, hard and yellow-brown. Both live in the soil and damage roots, but the controls differ. See our wireworms guide for the comparison.
Will the grubs kill my lawn? A healthy lawn usually recovers from moderate grub feeding, especially if it is watered and fed. Severe infestations can kill patches of turf, and animal digging for grubs can make it worse. Repairing the lawn and building up biological control is the long-term answer.
Do grubs attack vegetables? Yes, especially seedlings and young transplants with soft roots. Older plants with established root systems usually tolerate some feeding. Grow seedlings on until sturdy before planting out, and check wilting plants for root damage.
Is milky spore worth using? It can be, for Japanese beetle grubs specifically, but it works slowly and results vary with soil and climate. It is a long-term investment rather than a quick fix — check your local extension service for advice on whether it suits your area.
White grubs are a pest where counting before acting saves time and money. Lift the turf, count what is there, build up the lawn and the biological controls, and treat only when the numbers justify it. For the best-known grub species, see our Japanese beetles guide, and for general help use the pest identifier helper.