Extensive insect damage is often a sign of an unhealthy lawn. Apply the methods outlined for mowing, watering, fertilizing, and general maintenance. Your encounters with problem insects should lessen to an acceptable level.
Invite insect-eaters to your garden
- Many birds feast on adult beetles and/or beetle larvae.
- Bats are invaluable because of their voracious appetite for insects, many of which are considered pests especially in their larval form, such as the cutworm. In fact, bats are the primary predator of night-flying insects such as moths, beetles, and mosquitoes. A single bat can catch hundreds of insects in just one hour, consuming from 30 to 50 percent of its body weight in insects each night.
- Insect-eating bugs like ground beetles, dragonflies, and some non-stinging wasps are also beneficial in keeping a healthy balance in the garden
- Toads are another creature that gardeners are wise to attract. One toad can eat more than 1,000 earwigs in a summer.
Large infestations
If an infestation does occur and you need to act quickly, the following tips will help you identify the problem pest accurately and use appropriate organic controls:
Chinch bugs
These small red bugs with a white band across their backs can damage lawns by sucking the juice from grass. The black and white winged adults may also do damage. A sign of their presence is brown or yellow grass next to healthy grass or pavement. To determine if chinch bugs are the cause of your lawn woes, take a can with both ends cut out or some wide tubing, push it into the soil where you suspect the chinch bugs are feeding and fill with water. Chinch bugs will float up within minutes.
Eliminating chinch bugs
- Follow the above guidelines for a healthy lawn and you will significantly decrease the chances of chinch bug infestations. Pay special attention to fertilizing because too much nitrogen can cause excessive green growth and weaken the plant.
- Chinch bugs like dry conditions so water deeply in the spring, the time when they lay their eggs and the young hatch. The moist soil, according to Rodale Organic Gardening Basics: Lawns, will help a “naturally occurring fungus keep chinch bugs under control.”
- Keep compacted soil and thatch to a minimum to decrease places for these bugs to find shelter. A normal layer of thatch is not considered a problem when you have healthy soil full of beneficial micro-organisms. If you happen to cut very long grass and end up with a thick layer of thatch, you may wish to mow again to break up the thatch, or rake it to put on your compost pile, to deter these bugs from sheltering in it
- The Environment Canada fact sheet Alternatives to Pesticides — Answers to lawn care problems suggests spraying the problem area “with soapy water once a day for 10 to 14 days, or with a solution of a handful of wood ash and lime in eight litres of water.” Spread a flannel sheet over the treated area and, in less than half an hour, you should find bugs attached to the sheet, ready for disposal.
White grubs
These are the larvae of scarab beetles (Japanese, June, and Chafer beetles to name a few), which feed on the roots of grass and other plants. While a few in your lawn is normal, you know you have a problem when you find big yellow or brown patches of grass and a spongy sensation when walking on it. If you were to dig the area, it would lift up easily because the roots have been chewed up, and several white grubs with dark heads curved into a “c” shape would be apparent. If you find 10 or more grubs per square foot (108 per square metre), you could have a white grub infestation.
Eliminating white grubs
- Parasitic nematodes are living organisms of microscopic scale that will kill the unwanted grubs. Because the nematodes are alive, they must be handled with care. Read the instructions on the package very carefully. As a general rule, keep them cool at all times until they are moistened just before application. Do not let them sit in water and do not expose them to light (UV). Water the grass before application and then spray the nematodes on the lawn with a sprayer on an overcast day, or in the evening when the temperature is at least 15˚C, and keep the soil moist. Nematodes need to be placed where the grubs are and should be applied across the whole lawn, rather than in spot applications. You will have more success if the nematodes are applied when the grubs are small. This is often in the spring and late summer, but double check the grub you are dealing with and its life cycle to be sure.
- Strengthen grass roots to better resist grubs. Overfertilizing, as with quick-release fertilizers, can create soft, weak roots. Use natural fertilizer for slower, steadier growth all year. Mowing the grass to a higher level (don’t cut it too short) will also encourage a deep strong root system, as will deep infrequent watering. Avoid fertilizing in the summer because it could stress the plant at a time when lawns in most parts of Canada tend to go dormant or semi-dormant.
- Avoid over-watering the lawn in the spring when female adults are looking for moist grassy areas to lay eggs. If you do water, remember to water deeply and infrequently, which encourages the water to go deeper into the earth and allows the top layer to dry out in between waterings. Also, refrain from watering in the summer after the grass has gone dormant to reduce the survival of eggs and larvae.
Sod webworms
Signs of these insects are dead patches of lawn appearing in the late spring and on into the summer. Earlier in the spring, you can also watch for white moths that fly over the lawn preparing to lay eggs. The larvae live in underground tunnels and come out at night. You may spot them at night with a flashlight as they go about cutting grass blades and bringing them into their tunnels.
Eliminating sod webworms
- Try pouring a soapy solution on the affected area—about 30 millilitres (two tablespoons) of liquid detergent to 3.75 litres (one gallon) of water, according to Rodale Organic Gardening Basics: Lawns. This should bring the insects out of their tunnels to be collected and disposed of.
- Another recognized method is applying Bacillus thuringiensis (BT) two weeks after spotting adult moths hovering above your lawn.
- As with other pests mentioned, you should eliminate compacted soil and thatch where the pests can shelter and bare spots where the pests can flourish.
