Pocket Botanist
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Check these first
- Look for small caterpillars near the soil line.
- Check for silken webs or tunnels in the thatch.
- Examine the grass blades for irregular chewing patterns.
Likely causes
Sod webworms
PossibleHow to tell: You will see small, ragged patches where the grass has been chewed down to the soil. Look for small silken tunnels near the base of the plants.
What to do: Apply a lawn insecticide labeled for webworms in the late afternoon. Water the area lightly after application to help the product reach the soil surface.
Cutworms
PossibleHow to tell: These caterpillars chew through the stems at night, leaving patches of dead or dying grass. You might find them curled up in the soil during the day.
What to do: Use a biological control like Bacillus thuringiensis to target the larvae. Apply it in the evening when the pests are most active.
Find out what's wrong with your annual bluegrass
The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
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When to worry
Worry if you see large, spreading brown patches that do not recover with water. Minor chewing is normal in any outdoor lawn.
Stopping it coming back
Keep your lawn healthy and properly mowed to discourage pests from settling in. Avoid excessive thatch buildup.
Keep your annual bluegrass healthy from here
Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked. Identification and a health check are free.
Questions people ask
- Can I just pick the pests off?
- If you only have a few, handpicking them at night is effective. For larger infestations, a targeted treatment is better.
- Do pests cause the grass to die?
- They can kill patches if left unchecked. Early detection is the best way to keep your lawn looking green.
More problems with Annual bluegrass
Back to the Annual bluegrass guide
This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.