Couch Tip Maggot Control in Your Lawn

Information on Couch Tip Maggot is patchy at best, but this insect is a well-known pest on golf courses and turf grass production farms. The best thing you can do if you see damage such as wilted shoots and leaves in an otherwise healthy lawn, is to check those shoots for larvae. Open up the shoot as best you can and look for creamy fly larvae (i.e., maggots) up to about 5 mm long.

If you do find them, there is not a lot you can do. There are no insecticides registered specifically against Couch Tip Maggot in home gardens at this time. Any insecticide used would need to be systemic because the maggots are protected from contact insecticides inside the growing shoots of couch grass. All is not lost though. Evidence suggests that well-maintained healthy lawns can withstand an infestation of these flies and should recover well from any damage caused.

Prevention is the best thing you can do. That means keeping the lawn appropriately watered and fertilised. Yates Dynamic Lifter Organic Lawn Food is a gentle, slow release, and organic based lawn fertiliser that provides strong, healthy, and lush green growth, while organically enriching and improving the soil. Avoid over-fertilising as too much fertiliser will promote lots of new shoots, which is a magnet for the adult flies, so only apply Yates Dynamic Lifter Organic Lawn Food every spring and early autumn.

There is anecdotal evidence that hybrid couch grass varieties may be less affected by infestations of Couch Tip Maggot, but that is yet to be proven.

The Couch Tip Maggot is the larval stage of the fly Delia urbana, which is a member of the fly family Anthomyiidae. Several species within this family are horticultural pests, and are commonly referred to as ‘root maggots’ or ‘root flies’. This includes the introduced fly pest Delia platura known in Australia as the ‘onion maggot’. The Couch Tip Maggot Delia urbana is a little different in that its larvae (‘maggots’) don’t attack the roots of turfgrasses, but instead burrow into the growing tips.

The origin of Delia urbana is not certain but it is thought the flies might have been introduced from Africa into Australia. The fly is distributed in mainland Australia throughout southern Queensland, coastal NSW, southern Victoria, South Australia and south-western Western Australia.

Adult Delia urbana flies are about 4 mm long and similar in appearance to house flies but about half to two-thirds the size and slenderer. They are greyish, rather drab, hairy, slender and inconspicuous flies. Adults are more likely to occur during warm weather.

Larvae are legless maggots up to about 5 mm long.

Couch Tip Maggots pass through a life cycle of complete metamorphosis – eggs, larvae, pupae and adults. There are one to five generations per year depending on the climate.

Adult flies may be observed flying just above the grass, especially when there is a large infestation. Adult females lay their eggs, which hatch after a few days into larvae that enter and feed on the terminal shoot of the grass. Larvae pass through 3 instars over a period of two to three weeks growing ever larger.

• Couch grass (Cynodon sp.) is the principal host.

• Wilted leaves and shoots.
• Browning off of turf in patches.

• Look for adult flies flying just above the lawn.
• Check inside shoots for small maggots at the first sign of damage.

• Keep your lawn appropriately watered and fertilised.
• Stressed lawns are always more susceptible to attack from turf pests than healthy lawns.
• There is anecdotal evidence that hybrid varieties are less susceptible, but that has not been confirmed by testing.

• The natural enemies of Couch Tip Maggot in Australia are unknown.