Nothing really "eats" boxwood :-) They can get some - not many - insect issues but these all tend to be sucking type insects. But if the infestation is large enough, it can cause leaf drop.

I'm not absolutely sure what the issue is. The webbing is somewhat evocative of spider mites however I don't see any obvious sign of mite damage like stippling and discoloration.....the webbing could just be that of regular spiders and the basal dieback the result of the shading of the lower foliage. Or perhaps some chemical damage....boxwoods are sensitive to road salt.

Regardless, it is not anything that will necessarily remain present in the soil or a serious insect pest that would infest any replacements. Just hosing down the plants periodically will discourage any mites and avoid using deicing salt in the vicinity.

dont quite understand if you are removing all.. or just the bad ones ...

if all ... the problems goes away ...

if just some.. then you might have to further ID the problem.. and react ...

besides the pic.. you havent given us much to go on ... i find the consistent one foot high damage .. almost looking snow cover related or some such ... driveway salt... etc ... but it really doesnt matter if they are a knockin on deaths door ...

and .. btw ... they are jammed in that corner.. i would think its time for something new ...

ken

here is excellent data on boxwood diseases. In my case, losses were due to 2 years of severe drought followed by 2 years of above average rainfall. Addiitionally, my shrubs are close to 30 years old. It is not a good practice to plant same plant where a diseased plant was, but I've done it with nary a consequence. Personally, I will keep my boxwoods b/c I like the formal look they lend to a garden and they take pruning so well, but that's just my personal preference.

http://www.clemson.edu/extension/hgic/pests/plant_pests/shrubs/hgic2052.html