Maggot barriers are those little nylon bags you may be seeing on some apple trees. See an example at right (photo from Territorial Seed). They are quite effective in keeping apple maggot and coddling moth damage to a minimum. Some resources say something like 95% effective. That is pretty good.
You can see in the video listed below, the bags should be applied when you are thinning your baby fruit. You ARE thinning your baby fruit, right? :) So many things can go wrong with fruit production. This is one thing that can really help.
If you have no damage, and didn’t get this done earlier, it’s not too late. Apple maggot flies are active late June through October in Washington state. Codling moth pupae emerge about flowering time for apples, and generally 2-3 generations of this pest are produced from mid-April through September.
Read more about Apple Maggot.
Read more about Codling Moth.
How to apply the maggot bags:
Where to buy Maggot Barriers:
Territorial Seed — http://www.territorialseed.com/product/14802/natural_pest_control/?r=PWGBASE&gclid=CMywptmAjcYCFUSRfgodBLcAHw
Maggot Barriers — http://www.maggotbarriers.com/purchase/
Raintree Nursery — http://www.raintreenursery.com/Apple-Maggot-Control-Bags-144-Bags.html
Disposable foot sox are the same thing:
Amazon — http://www.amazon.com/Disposable-Foot-Socks-DISPOSABLE-Gross/dp/B0084DWAQW