Lawn pests like grubs and mosquito larvae damage lawns by eating grass roots and stems. The aftermath is often those unexplained brown, dry patches you keep noticing in your lawn. When grubs and other insect larvae feed on grass roots, your lawn root system is compromised, and your grass can’t receive the nutrients and moisture it needs to thrive.
However, to prescribe the correct lawn-pest control, you’ll need to identify the insects damaging your lawn, as there is a huge variety of insects out there. Some are helpful lawn bugs like pollinating bees or earthworms, which help improve water infiltration and soil aeration; others less so. The owlet moth, for instance, will use your lawn as a nursery for their larval offspring, while the armyworm will feed on the grass root system.
All lawns and landscapes are full of bug life, but only 1% of all insect species are considered pests. So, using broad-spectrum insecticides isn’t the best form of lawn-insect control, as you’ll be killing useful insects as well as pests.
A basic understanding of the insect is required to control lawn pests effectively. Knowing a lawn pest’s life cycle will help you determine the best control measures and when they will be most effective (i.e. when the insect is most vulnerable).
In this list, we’ll identify some of the biggest offenders in terms of lawn-damaging insects alongside pictures and information about their life cycle.
Garden Grubs Identification
Grubs are the larval stage of several species of beetle. White grubs are probably the most common lawn grub you’ll come across in the States. They’re the larvae of the European chafer and Japanese beetle.
Grubs are one of the worst lawn pests as they feed on grass underneath the soil at root level, so they’re not easily visible. But there are some signs you can look out for which might indicate a grub infestation:
- Moths, beetles, and other animals — If you begin spotting lots of moths and beetles flying above your lawn, this could be a sign your grass has a grub infestation. Moths and beetles are looking for somewhere to lay their eggs, which hatch into larvae. Animals like birds, raccoons, and skunks might also be more frequent visitors. They are likely searching for grubs to eat by digging up or sniffing around your lawn.
- Bouncy turf — Grubs feed on the grass roots, so the connection between the surface turf and root base becomes weak. This results in spongy or soft grass, which might indicate grub activity.
- Brown patches — Dead, yellow, or brown dry patches in your grass can also be evidence of grubs — but these dead patches can also be due to drought or certain lawn diseases like brown patch.
It’s easy to tell the difference between certain insects but not their specific larvae. Different species of insect larvae can look identical — aside from a few tiny variations.
Below, you’ll find how to identify common lawn grubs before you move on to learning how to treat them.
White grubs have brown heads with three pairs of legs and are often found lying in a C-shape. If you see a brown patch in your grass and suspect it’s a grub infestation, dig it up. More than five grubs per sq. ft can indicate an infestation.
Similar in appearance to white grubs, billbug larvae are creamy with brown heads. Unlike white grubs, however, they have no legs and can range from a quarter to half an inch long.
A good indicator of billbug grubs is their feces — a light-brown sawdust-like material you might spot in and around your grass base.
Japanese Beetle Larvae
Another example of a white grub, Japanese beetle larvae have comparatively light-tan heads. Their legs are also longer than most other grubs and easily visible.
In size, they range from about an eighth of an inch to an inch long. They also have hairier spines than their smoother counterparts.
Masked Chafer Grubs
The larvae of the masked chafer grow up to an inch in length. They’re distinguished by dark, translucent stripes on an off-white body.
Underneath their abdomen, masked chafer grubs have a scattering of bristles at one end. May or June beetles look similar in appearance but instead have two parallel lines of bristles on their abdomen.
The Grub Life-Cycle
Scarab beetles, like the Japanese beetle, have a one-year life cycle. In contrast, June beetles have a three-year life cycle. When you’ve identified your grubs, look up their particular life cycle to work out when adults lay their eggs. For most beetle species, this is during early midsummer, when mating and egg-laying take place over a couple of weeks.
Beetle and moth eggs will hatch approximately two weeks after being laid in mid-to-late summer. Mid-to-late summer is the best time to target lawn grubs, as it’s when they’re most vulnerable. Brown or dry patches of grass form in the fall or spring, which is when the grubs start feeding on your grass.
To treat grubs, we recommend using Acelepryn, which will target most lawn grubs, billbugs, and more without eliminating useful insects like bees and earthworms.
Other Lawn Pests
Grubs aren’t the only lawn-damaging insects out there. Let’s look at some other lawn pests and how to identify them.
The armyworm is the larval form of fall moths, commonly the owlet moth or armyworm moth. Despite its name, it’s a caterpillar, around one and a half to two inches long, and is either dull green, gray, or beige with stripes along the length of its body. Along the top of the body is a broad band of gray with a net-like pattern on its brown head. You’re most likely to spot these pests during cooler temperatures or at night.
The armyworm life cycle occurs for a month (usually starting around June) during the summer and two months during spring and fall.
Chinch bugs are most common in southern or western US states. They feed off the moisture from your grass, leaving behind a poison that turns grass brown or yellow before killing it.
Adult chinch bugs are identifiable by their oval shape, black bodies, and white, overlapping wings. They’re small, at a fifth of an inch long, and have a black triangle near their head. Adult females lay eggs in the spring and continue throughout the summer if the weather is particularly warm.
Snout moth caterpillars, or sod webworms, like to feed on grass, leaving behind bare patches of grass. They’re fleshy-bodied, ranging from three-quarters of an inch to an inch long. Depending on the species, colors may vary (gray to pink)— but they tend to have dark heads and small spots on their bodies. Larvae can be found from March through to early November as adults migrate over in May to lay eggs.
Cutworms are the destructive caterpillars of various moths (mainly night-flying moths), living in the soil and eating grass stems, cutting grass at its base and taking it away to eat it later. Cutworms come in a variety of colors, ranging from brown, black, pink, and green. They have long stripes running the length of their bodies and curl up into a “C” shape when disturbed or exposed to the air.
Cutworms emerge in the spring — the best time to use your chosen insecticide on your lawn for this pest.
Billbugs are lawn pests at all stages of their life cycle. As larvae, they eat grass, and as adults, they chew grass stems to lay eggs inside. Billbug damage is easily mistaken for disease or drought, but if you can pull up grass that breaks at the soil line, you might have a billbug infestation on your hands.
A kind of weevil, billbugs can grow to half an inch long. Their bodies are brown or black with a long downwards-curving snout. Adult billbugs lay eggs in June, which hatch into small larvae that feed on grass stems for about two weeks.
Another all-rounder for lawn damage, fiery skippers feed off grass in their moth form and larval state. As larvae, they’re an inch long with pinky-green colored fleshy bodies. Their heads are oversized and usually black with red markings at the front. In adult form, they look like butterflies. Males have bright orange and yellow wings (hence the name), and females have dark brown wings with orange or yellow spots.
As soon as the weather starts warming up, fiery skippers will begin laying eggs on the underside of leaves.
Japanese beetles are an invasive species known to feed on the flowers, leaves, and fruit of over 300 different plants. They’re known to do serious lawn damage in adult form as well as in their larval stage, eating grass leaves and blades.
Japanese beetles are easy to identify. They’re usually around half an inch long with bronze and metallic green wing covers. On either side of the abdomen are six tufts of white hair.
Japanese beetles are most vulnerable during their larval stage, from April to May. In October, this larva burrows deep into the soil to remain inactive all winter before emerging again in the spring.
Mole crickets spend the majority of their time underneath the soil. When they emerge, they feed on grass foliage. Mole crickets are aptly named as their enlarged forelegs look like a mole’s front claws. They’re tawny brown or brown in color, measure around an inch long, and are easy to spot with their lobster-like head.
April-May is when most adult mole crickets lay their eggs — prime time for larval development. Adults and nymphs can still be found during August-September, so keep an eye out for dead grass in the late summer.
Greenbugs, also known as aphids, are widespread lawn pests. They’re often found in concentrated colonies on the underside of leaves. Greenbugs are very small, bright green, and oval-shaped, ranging from one to two millimeters long. Able to reproduce astonishingly quickly, greenbugs have toxic saliva that destroys chlorophyll in leaves and grass blades, turning them red or rusty brown.
Greenbugs favor warm weather to mature, so you’ll likely notice them in the summer. Check the underside of your plants and grass blades to see if you’ve got a greenbug infestation.
Black Grass Bugs
Black grass bugs are common in the west and enjoy piercing grass and other ornamental plants to suck the nutrients from the inside of the plant. Black grass bugs leave behind yellow and white spots on the grass, giving it the appearance of frost in severe cases.
Black grass bugs are black and around a quarter of an inch in size. They have little hairs lining the edges of their wing cases, with white markings on their heads and large protruding eyes. Eggs hatch the moment turf begins to green up in April and May, as nymphs prefer tender, young grass.
Lawn Insect Control
Now, you should have a comprehensive idea of lawn-pest identification. From this, you can understand better the damage these insects do and when they’re most vulnerable to treatment.
The key to preventing lawn-pest infestations is early detection. Looking out for the signs of pests or digging up areas you think might be affected early on is the best way to mitigate long-term lawn damage. Once you’ve identified the pest, you can move on to treatment. If you’re looking for how to repair your grass after insect damage, take a look at our other article on lawn pest management.