Common Lawn Pests
Pest Identifier
Our practical guide for grass pest identification
Several insects and mites feed on your lawn, but not all of them cause health or aesthetic damage. While many insects are harmless and even beneficial, some are pests. Only a few cause enough damage to be a problem and they need immediate control.
At Lawn Doctor we believe that correct identification of a pest can save money and prevent unnecessary pesticide applications.
Insects are only one of many potential causes for thin or brown grass. Turf diseases, environmental stress and nutritional disorders can also be damaging. Try to see the grass insects for yourself to confirm it is a pest.
Two Spotted Mite
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Two Spotted Mite (Tetranychus urticae) larve hatches from the egg has six legs, is pale yellowish-white, oval and minute. The larva moults to become an eight-legged nymph, which becomes the mature mite after two further moults.
The adult female is about 0.5 mm long and the adult male is about 0.3 mm long. In the summer feeding stage the adult females are a yellowish-green, with two obvious dark spots, one on each side of the body. In males these spots are less conspicuous. Both sexes possess two reddish eyespots. Only adult females overwinter, after changing to the orange-red, non-feeding stage.
Both nymphs and adults damage plant foliage by piercing the cells and sucking the contents, collapsing the cells killing the leaf. The mite is a spins webs in its active stages. Populated leaves become pallid and may become bronzed and shrivelled. The mites are more damaging in hot, dry weather with shorter life which can be in just over a week. Lawn near dust sources such as dirt roads are particularly susceptible to mite attack.
The mites leave their hibernating sites from winter and lose their red colour as they start to feed. The females lay up to six eggs a day and usually lay a total of 70 or more. Hatching occurs three to 10 days later, depending on the temperature.
The use of miticde greatly reduces the number and effectiveness of beneficial insects, plus mite populations have developed varying degrees of resistance to several miticides. If chemical control is required, careful selection of a miticide is important. There are several effective miticides available but they can be poisonous.
Sod Webworm
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Sod Webworm (Herpetogramma licarsisalis) is a thick caterpillar up to 25 mm long, with a pale green-brown body that is marked with characteristic dark spots along its length.
When mature the adults become a slender-bodied moth with a wingspan of 2.5 cm. Their wings are grey with black spots and transverse dark, wavy lines.
Female sod webworm moths drop their eggs onto turf while flying at night. The eggs fall into the thatch and hatch within 10 days, depending on temperature. Peak hatching occurs in early summer and continues throughout the summer months. The eggs tend to be oval or elliptical in shape with longitudinal ridges on the surface that run from pole to pole. Upon hatching larvae burrow into the thatch and conceal themselves. These larvae remain concealed during the day and wander out at night to feed.
By late spring or early summer the young adult moths emerge and fly just above the turf. These moths are active at dusk. The entire life cycle generally takes about six weeks, and in most regions this pest has two to three generations per year.
The larvae feed at night and eat the tender leaves and stems. This injures the turf causing brown patches. It can look like fungus, but if you look closely you will see the edges of the leaf may be ragged where the larvae has been feeding.
Pruinose Scarab
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The pruinose scarab larva is a white to creamy-white soft-bodied grub, up to 20mm long with 3 sets of legs and a hard light brown head capsule. As with most scarab pests, the larvae can be difficult to identify between species as only subtle characteristics distinguish them from other beetle larvae. When mature the adult beetle possesses a dark brown to black carapace up to 16mm long and has a unique set of antenna with have large club-like ends. The underside of the body is covered in short grey hairs.
Adults emerge from pupation under the soil in early spring, and often fly to eucalyptus trees to mate before returning to the soil to lay 20-40 eggs. The larvae then hatch and burrow into the soil where they remain for a period of 8-10 months before emergence the following spring. Larvae will mainly eat decaying organic matter though in plague proportions they will eat turf roots. Adults then hatch in spring and live for 1-9 weeks.
They can become a plague after a warm, dry winter. Severely affected turf has the roots completely eaten away & when it is peeled back, you will see the white grubs.
Mole cricket
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Mole crickets are cylindrical-bodied insects about 3–5 cm (1.2–2.0 in) long as adults, with small eyes and shovel-like fore limbs highly developed for burrowing (just like their namesake – the mole!). Australia is home to a number of invasive mole cricket species, including the African mole cricket (Gryllotalpa africana), native to Africa; and the Changa mole cricket (Scapteriscus didactylus), which has been accidentally introduced to areas around Newcastle. We also have our own native species of mole cricket, Gryllotalpa pluvialis, found mostly on the east coast. Usually we see mole cricket damage in Spring & Summer.
Some species harm turf through tunnelling and uprooting grasses, but others feed heavily on roots and dine on tender shoots on the surface. Few tiny seedlings are safe. Uprooted seedlings and raised, molelike runways just below the soil’s surface show where their spade like front legs have tunnelled through soil. By the time dead turf becomes visible in late summer, mole cricket damage is done.
You may also hear the mole crickets make a chirping or trilling sound, often at dusk. Egg laying has been observed to begin from November throughout the warmer months. Adult females construct egg chambers depositing up to 200 eggs with each egg measuring 2mm in length. Within two weeks of laying, the eggs hatch and become young nymphs that resemble adults. While adult male mole crickets die after mating, females die after depositing their eggs. There appears to be only 1 generation of insect per year in Australia.
Mealybug
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Found in warmer growing climates, mealybugs are soft-bodied, wingless insects that often appear as white cottony masses on the leaf.
They feed by inserting long sucking mouthparts, called stylets, into the leaf drawing out sap out of the tissue. Damage is not often much. However, at higher numbers they can cause leaf yellowing and curling as the plant weakens.
Mealybug sizes range from approximately 2 mm to 6 mm in length. Adult females deposit 300 to 600 eggs within an excreted, compact, waxy, cottony-appearing mass mostly found on the underside of leaves (these egg cases can be confused with mould). Egg laying lasts for about two weeks, with the female dying shortly after all eggs are laid.
Hatching occurs within one to three weeks and the small, active yellow nymphs begin migrating over the plant in search of feeding sites. As they feed, they secrete a waxy coating over their bodies.
Lawn Armyworm
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Lawn armyworm (Spodoptera Mauritia) is a damaging pest when in the larval life stage. The larvae are a soft-bodied caterpillar with a dark-coloured body up to 45 mm long. They possess unique white and yellow striped patterns along the length of the back making them relatively easy to identify.
When feeding the larvae often appear in congregations, clumping around stems and foliage of the turf plant.
Once mature, the caterpillar metamorphoses into a pale brown moth with a wingspan up to 40 mm and possesses a distinct white spot in the centre of the fore-wing.
The newly hatched armyworms stay together, feeding on turf leaf and stem until it is devoured. The larvae lawn armyworm are usually most active in the evening or at night, except in overcast weather conditions. During the day they hide under the safety of the lower grass leaves.
An armyworm will undergo six to nine instar stages before it is fully developed. This will take 21 to 35 days and at a mature instar stage the insect will reach 3 to 4 cm in length. When fully fed the armyworm will work its way into the soil profile where it pupates. Ten to 14 days later the moths emerge. There could be two to three generations of armyworm during the summer/autumn period.
Argentine Stem Weevil
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The immature or larval stage of the Argentine Stem Weevil (Listronotus bonariensis) is a legless, creamy-white, active larvae up to 4 mm in length. When mature, the adult appears as a dark grey to black weevil with mottled grey body markings and a distinctive protruding snout, up to 3 mm in length.
Adult weevils emerge from overwintering sites between September and November. After mating the female weevil deposits several eggs under the leaf sheath of the host plant. Once the eggs hatch the larvae begin to feed inside the plant stem until they reach the second or third instar, at which point they burrow out of the plant and drop to the ground.
Once outside the plant, the larva begins to feed at the base of the turf plant, ingesting plant material from the stems and crown.
Argentine Stem Weevils are a serious pest in turf.
Argentine Scarab
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Sod Webworm (Herpetogramma licarsisalis) is a thick caterpillar up to 25 mm long, with a pale green-brown body that is marked with characteristic dark spots along its length.
When mature the adults become a slender-bodied moth with a wingspan of 2.5 cm. Their wings are grey with black spots and transverse dark, wavy lines.
Female sod webworm moths drop their eggs onto turf while flying at night. The eggs fall into the thatch and hatch within 10 days, depending on temperature. Peak hatching occurs in early summer and continues throughout the summer months. The eggs tend to be oval or elliptical in shape with longitudinal ridges on the surface that run from pole to pole. Upon hatching larvae burrow into the thatch and conceal themselves. These larvae remain concealed during the day and wander out at night to feed.
By late spring or early summer the young adult moths emerge and fly just above the turf. These moths are active at dusk. The entire life cycle generally takes about six weeks, and in most regions this pest has two to three generations per year.
The larvae feed at night and eat the tender leaves and stems. This injures the turf causing brown patches. It can look like fungus, but if you look closely you will see the edges of the leaf may be ragged where the larvae has been feeding.
African Black Beetle
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Newly hatched African Black Beetle (Heteronychus arator) larvae are about 5 mm long with six legs, white bodies and pale brown heads. Fully grown larvae are 25 to 30 mm in length with a creamy-white body and light-brown head. The rear end has a dark grey tinge.
When resting the grubs curl into a C-shape. The adult beetle is a rich chestnut colour when newly emerged, but changes to a shiny black, stout-bodied beetle approximately 10 to 15 mm long.A major pest in turf, most damage is caused by larvae feeding on the underground stems of young plants, often killing growing points so that the central shoots wither and the plants become dead-hearted.
The African Black Beetle only needs two consecutive dry years to reach plague proportions.
Adult beetles in spring are attracted to lush grass to feed and lay eggs on. The larvae then feed on roots and compromise the plants ability to source water, resulting in drought-like symptoms