Have you noticed brown patches appearing in your lawn? Does your grass come up easily when you pull on it, almost like a loose carpet? Are birds constantly digging holes in your lawn, or have foxes and badgers been tearing up patches of turf overnight looking for a snack?
If any of that sounds familiar, chances are the real problem isn't happening on the surface it's happening underground. Chafer grubs, leatherjackets, and sciarid fly larvae feed on grass roots for weeks or even months before you ever see a sign of trouble. By the time the brown patches show up, the roots underneath are often already badly damaged, which is why the grass pulls up so easily there's nothing left holding it down.
The good news is that catching these signs early gives you a real chance to fix things before they get worse. A lawn that's just starting to thin out and discolor can usually bounce back quickly once the larvae are dealt with and the roots are given a chance to recover. Wait too long, though, and you're often left reseeding bare patches from scratch.
The Hidden Enemy Beneath Your Grass
Most people notice lawn damage long before they ever see the culprit, because the real damage happens underground. Three larvae are usually responsible:
-
Chafer grubs - the larvae of beetles like the May beetle, June beetle, rose chafer, and salland beetle
-
Leatherjackets - the larvae of the crane fly (daddy longlegs)
-
Sciarid fly larvae - small larvae that also attack grass roots
All three feed voraciously on grass roots just below the surface. Once the roots are damaged, the grass can no longer take up water or nutrients properly, and patches of lawn turn yellow, thin out, or die off entirely. To make matters worse, birds, foxes, and badgers will often tear up the damaged turf hunting for the grubs themselves turning a hidden problem into a very visible mess overnight.
An Interesting Fact About These Pests
Here's something most gardeners don't realize: a single female May beetle or June beetle can lay dozens of eggs in lawn soil in a single season, and the larvae can live underground for one to three years before emerging as adults, depending on the species. That means an infestation you notice this autumn may actually have started developing quietly the year before. This is exactly why a preventive approach strengthening the grass before damage appears tends to work far better than waiting to react to visible damage.
How to test for leatherjackets:
Water an area of the lawn thoroughly, then cover it with black plastic sheeting overnight. In the morning, remove the plastic and count how many leatherjackets have come to the surface. A small number is completely normal and nothing to worry about. Large numbers, especially combined with yellow or bare patches, are a sign of a real infestation.
How to test for chafer grubs:
Cut out a small section of turf, roughly 20 × 20 cm, in several different spots around the lawn, and count the grubs you find among the roots and soil. As a rough guide:
-
0–5 per m² — no real infestation
-
5–25 per m² — moderate infestation
-
More than 25 per m² — severe infestation
A useful shortcut: finding just one chafer grub in a single 20 × 20 cm patch already works out to around 25 per m², so it's worth checking a few different areas rather than judging your whole lawn on one sample.
Fortunately, there is a natural way to stop the problem before it destroys your lawn.
Instead of reaching for harsh synthetic fertiliser, Organifer's Grass Insects Concentrate works with the grass itself, strengthening its roots and natural defenses so chafer grubs, leatherjackets, and sciarid fly larvae simply lose their appetite for it. It's a gentler approach, but one that tackles the problem at its source rather than just masking the damage on top.
Grass Insects Concentrate - 250 ml for 62 m2
Choose your option
Grass Insects Concentrate - 1000 ml for 250 m2
Choose your option
Grass Insects Concentrate - 500 ml for 125 m2
Choose your option
Grass Insects Concentrate - 5 l for 1250 m2
Choose your option
When Is the Best Time to Apply It?
Timing makes a real difference with lawn larvae treatments, since it lines up with the pests' natural life cycle:
-
Late summer to early autumn is generally the prime window, since this is when eggs have recently hatched and young larvae are actively feeding near the surface, making the grass's natural defenses most effective against them.
-
Spring can also be a good time, targeting larvae that overwintered in the soil before they mature and pupate into adult beetles or flies.
-
Apply the solution during rainy weather for the best absorption, and if conditions are dry afterward, water generously to help the concentrate reach the root zone.
-
Grass Insects Concentrate can be used both preventively and curatively — so even if you already see signs of damage, it's not too late to apply it.
A Simple, Sustainable Addition to Lawn Care
For anyone trying to move away from synthetic fertiliser without compromising on lawn health, Grass Insects Concentrate is an easy product to fold into a regular seasonal routine. A couple of well-timed applications a year - paired with good watering practices - can make chafer grubs, leatherjackets, and sciarid fly larvae far less of a threat, while actively building a stronger, healthier lawn in the process.
If you've been battling patchy, damaged turf and suspect larvae are the hidden cause, this is one of those rare lawn treatments that fixes the immediate problem while making your grass more resilient for the seasons ahead.
