How to deal with fall’s unpleasantries
September 8, 2008 · Updated 4:38 PM
It’s nearly the first day of fall. Along with the approaching date we’re also experiencing fall webworm infestations. Don’t panic though, these caterpillar tents and moth larvae are nothing like the spring into summer onslaughts of tent caterpillars we sometimes encounter.
Fall webworms spend nearly their entire life encased in their caterpillar-made tents. Drivers on Highway 3 heading north and south have probably seen these tents on the outer limbs of the alders. Fall webworms also build nests in fruit trees, cottonwoods, birch and other deciduous trees. Luckily, these caterpillars are eating machines that live inside the tent. Also luckily, it’s a time of year when the trees are going dormant anyway. This is a very good thing. These caterpillars will soon be gone.
I’ve written a column on fall webworms nearly every September, so we’re right on schedule. If you have internet access visit these sites for photos and more information on fall webworms: http://cru.cahe.wsu.edu/CEPublications/eb0827/eb0827.pdf and http://kitsap.wsu.edu/hort/dig_this/dig_this_toc.htm. Look under September for each year.
Bottom line on fall webworm — usually gardeners need do nothing, unless it’s a horrible infestation or when growing fruit trees for harvesting. If you need to destroy the nests, cut them from their host plant if possible or strip the webs off. Drop the webs and caterpillars in a bucket filled with soapy water. If your garden is frequently visited by fall webworm and control is needed, next year when the webs begin to form, open the webs and spray with Bacillus thuringiensis Bt. This bacteria will be ingested by the larva as they feed on the leaves. Remember for Bt to work it must be ingested.
This is also the time of year when apple maggot signs show up in harvested fruits. Visit http://skagit.wsu.edu/Agriculture/com_saveapples.htm for abundant information on apple maggot and how to control this pestiferous insect. One thing every one of us can do is pick up and dispose of any fallen apples we see in our neighborhoods and in our own gardens. The trick is to pick up and dispose of fallen fruit every day. Don’t leave the fruits on the ground to rot. This applies to all fruit actually. Sanitation is a very good insect pest protection method.
Apple maggots are the larva of a fly. It has classic black and white stripes on its wings. The fly inserts its eggs into apples. Look for small black spots on the outside skin of the fruit. When the larva hatches it works its way through the fruit leaving bacterial trails turning the inside of the fruit brown and mushy. Sometimes before we even cut the apple open we can see brown bruises on the outside of the fruit. We soon discover the discolored and very unappetizing inside. Do not eat or preserve this fruit because of the bacteria.
Visit http://cru.cahe.wsu.edu/CEPublications/eb1928/EB1928.pdf for complete information on apple maggot and also on coddling moth. Fruit with coddling moth damage can be salvaged by cutting out the damage, but fruit infested with apple maggot needs to be discarded. Do not compost apple maggot infested fruit. Bag it up and send it to the land fill. Call the Master Gardener hotline at (360) 337-7158 to request a copy of the referenced publications if you do not have access to the Internet. Or stop by a local Kitsap Regional Library branch for internet access to read the publications.