Question
Dear Floyd
We recently moved(in mid-July)to Angmering in W Sussex.
We understand that the plots on this newly-built estate were built on a very large nursery site with extensive greenhouses. The soil seems very clayey, shallow and poor.
When we inherited our new garden, the lawn looked healthy and green.It didn't have,and still hasn't moss or weeds.Then a small dry patch started in one corner, and we noticed the blackbirds often coming to the lawn and pulling out tufts of grass and pecking at something below the tufts. The 'death' of the lawn seemed to spread from there, and now has taken over almost 3/4 the area of about 70sq meters.The birds continue to decimate the lawn, so these upturned tufts lie all over the dry area!
Is our problem dryness, or is it a bug that is 'eating' the grass? We haven't watered it since being here, as there is a water restriction in our area.
Should I place a top-dressing on it now and how can I know whether this is disease or not?
Thank you.
Diana  

Answer
Good evening Diana:
From your description, I believe you have Sod Webworm. The adult moth is ?inch long, light tan or buff colored, and holds the wings close against the body in a tubelike fashion when at rest on a grass blade. When disturbed, the moth will fly in a dipping, zigzag pattern just a few feet above the turf. The caterpillar is gray or greenish, up to 1inch long, slender, and covered with brown spots.  The caterpillar emerges at night from a silk-lined tunnel in the thatch and will eat grass blades down to the crown.
Attacked turf has irregular brown areas because the grass blades are gone, allowing the thatch to show. Green, 1/8 inch diameter feces are numerous at the base of attacked turf. Damage usually occurs during dry periods of the growing season.
The birds you see are digging with their beaks to get to the caterpillars. They are actually helping you get rid of the sod webworm.
Chemical insecticides are effective. Damaged turf usually recovers with irrigation (after the caterpillars are controlled) because the undamaged crowns and roots are able to grow new leaves.
Some web sites that can help you in control of the Sod Webworm are: (Copy and paste to your browser then hit "GO").
http://ohioline.osu.edu/hyg-fact/2000/2011.html
http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/sodwebwm.htm
http://www.utextension.utk.edu/publications/spfiles/SP290-L.pdf
http://ipm.montana.edu/YardGarden/docs/sodwebworms-insect.htm
I hope I have helped. Have a good lawn!
Floyd McMahon