Here are some of the possibilities.
White Grubs
This incredibly unattractive insect is “C” shaped with a brown head, white body, and 6 legs on its upper half. White grub is just one part of the life cycle of the June beetle, Japanese beetle, and the European Chafer beetle. Eggs are laid in the lawn in late June, early July. These eggs hatch into grubs that begin to feed on the roots of your lawn in late July to August. They continue feeding and growing through the fall when they burrow below the frost line to overwinter. As soon as the ground starts to warm in spring, they rise and start feeding again in March/April. It’s at this time you may first become aware you have a problem because raccoons and skunks will nightly rip back sections of turf to feed on them. The Grubs continue to feed and grow until mid-May when they develop into their final pupal form. The adult beetle emerges in mid-June, mates, and the females return to the soil to lay their eggs. And the cycle starts all over again. Breaking this cycle can take several years.
The second indication grubs may have invaded your lawn are patches of brown, dead grass. If you can pick up this grass in handfuls there are no roots holding the blades firmly in place. Grubs have consumed the root system. If you lift healthy turf nearby, you’ll probably see them. If left unchecked, your lawn will be completely destroyed because grass simply can’t survive without roots.
Grub Control
There’s only one completely natural pest control that’s currently available. It’s composed of active agents called infective or “beneficial” nematodes. These microscopic worms enter the grub, release bacteria, reproduce in the host, and kill it. The nematodes then vacate the dying insect and seek a new host. All vertebrates (humans, dogs, birds, etc.) are completely resistant to nematodes as are plants, earthworms, and helpful insects like bees and ladybugs.
Beneficial nematodes are also the natural way to control the following garden pests:
- Cutworms
- onion maggots
- fungus gnats
- carrot fly
- white grubs (June bug larvae)
- sod webworms
- borers
- fleas
- vine weevils
To apply nematodes to your lawn when the soil has warmed up in June, water the affected area for an hour or after a heavy rainfall is the best time for application. Place the product in a hose end sprayer having removed the filter first. This is especially important to avoid trauma to the nematodes. Mixed with water, nematodes will move quickly through the pre-moistened soil. For small areas, it can be mixed with water and applied with a watering can.
Through June and July the nematode population will rapidly increase from the few originally released. If your neighbourhood is infected with grubs, your chances for re-infection are automatic. Keep applying nematodes for 2-3 years until you’re confident your lawn is grub-free.
Another natural method of control is to keep your lawn as healthy as possible. Grubs seem to feed on weaker lawns. Regular applications of fertilizer, lime and over-seeding will keep grass strong and increase root production. Minimize thatch build-up so that fertilizer, water, and air can pass into the root zone easily. If you don’t have a dethatching lawn mower, rake all clippings off the lawn and use a dethatching rake to remove the solid build-up of old clippings. Keep your lawn well watered with 2.5 cm – 4 cm (1” – 1.6”) of water per week. If your schedule is too hectic to achieve this, consider installing an in-ground irrigation system so you can set a timer for regular intervals.
To keep raccoons and skunks from digging up the lawn in spring and fall, lay well-anchored chicken wire over the area that can be rolled up and reused as necessary.
Chinch Bugs
This insect is quite small, bright red when young, deepening to dark red, and finally dark grey with white patches when fully mature. Chinch Bugs suck the juices from the crown and stems of grass with their piercing mouthparts. They inject a poison that causes blades to turn brown and die. They can cause considerable damage especially in sunny areas of the lawn. They’re most active during hot, dry weather. To test if you have them, cut the top and bottom off a large juice, coffee, or vegetable can. Force the open-ended can into the grass to half its depth and fill it with warm water. If there are Chinch Bugs in the vicinity they’ll soon float to the surface since they don’t dwell below ground like grubs.
For natural control, reduce the use of fertilizer high in nitrogen and sow grass seed with perennial ryegrass that’s been endophyte enhanced. Endophyte naturally occurs in many perennial ryegrasses and some fescues and is a deterrent to chinch bugs and other surface feeding insects.
Sod Webworm
The adult sod webworm is a small, whitish-grey moth that flies up in zigzag patterns when you walk across the lawn at dusk. The larvae are slender, greyish, black-spotted caterpillars that hide during the day.
Overwintering larvae emerge and begin feeding at night or on overcast days in spring. They mature into moths in early summer. Throughout the summer, the moths fly over and drop their eggs into the lawn. There can be as many as three generations per season. Damage by sod webworm is characterized by grass blades chewed off or skeletonized just above the thatch line.
Natural controls include the use of beneficial nematodes, Bt (Bacillus thuringiensis), Pyrethrum, and resistant grasses that are endophyte enhanced.
May 2020
