I have a lawn infested with some kind of moth. They've been active since the spring but now I'm seeing small worm like caterpillars throughout the grass. Also the grass looks like it's been eaten. I'm pretty sure these moths are laying eggs in the grass and these caterpillars are their young but I don't know where to start treating. What can I use? I've got about 10,000 sq/ft of lawn they're in.
It sounds like you've got sod webworms. Some people call them lawn moths or moth worms; these are a lawn pest which eats grass and lives in the turf. The adult moth doesn't eat grass but it does lay a lot of eggs. Typically the eggs fall out over the lawn and over the course of the summer these eggs hatch out small caterpillar like worms that feed on the blades of most any turf grass found in the United States. They'll munch and eat for a month or two and then spend another month pupating into an adult stage.
Once they hatch out to their adult moth phase, males and females mate and females start laying eggs over the rest of her lifetime. In the south, webworms can generate 3 generations a year. Up north there is usually 1-2 cycles per season. At the end of the summer, the feeding, young caterpillars will go dormant in their pupae stage and hibernate during the winter. They do this down in the soil and there they'll stay till the following spring. If left untreated, small populations will grow annually until their impact will be very noticeable one season. In the spring when they first emerge, it's hard to see them but late summer the damage they do will become very noticeable as populations peak.
Sod webworms can be controlled using a combination of granules and liquid sprays. BIFEN GRANULES should be spread out over the turf at the rate of 25 lbs for every 20,000 sq/ft. Treatments should be made every 2 months during the warm season with at least 4 treatments per year. The granules are slow release and will filter down into the ground a few inches where they'll control larvae as they hatch. These same granules will also get late season caterpillars making their way into the soil to hibernate effectively stopping the cycle.
After applying the granules you should spray over the top with CYONARA RTS or CYONARA CONCENTRATE. Both are highly active on webworms and will quickly kill off any active in the treated areas. Liquid treatments should continue every two weeks if you still see damage or live worms moving in the grass. The RTS version comes packaged in a hose end sprayer so all you need to do is attach it to your garden hose and start using it. The concentrated version will require a good HOSE END SPRAYER for the treatment but will prove more economical if you have a large area to treat over the course of a season. Cyonara is active on a wide range of turf pests, is just about odorless and very safe to use in yards where people or pets are active. When treatments are timed properly, you should be able to eliminate the average infestation with just 1-2 applications of both the granules and the liquids.
Here are direct links to the information and products listed above:
Bifen Granules: http://www.bugspray.com/item/453410.html
Cyonara RTS: http://www.bugspray.com/item/cyonara_rts.html
Cyonara Concentrate: http://www.bugspray.com/item/cyonara_ec.html