The South Marysburgh Mirror Natural South Marysburgh Fall Webworm Showing Up On Trees Now -By Terry Sprague | haven’t seen any yet as | am writing this, but they will appear very soon. They always do. lam talking about the webbing we see every August that covers the branches of trees. No, these are not tent caterpil- lars as some believe. The masses of webbing belong to fall webworms. It is native to North America, but was introduced to what was formerly fugosavia | in the 1940s—sources don’t say whethet and has since spread across Europe from trance to the Caspian Sea as it penetrates central Asia. It is also in Japan, China and Korea. Turns out it is actually one of the few insect pests that we have exported! Oops! Another success story for an invasive species that is impacting those countries, much the same as their native spe- cies like purple loosestrife, garlic mustard, phragmites, zebra mussels, and starlings, have gained a foothold here. Here, the fall webworm is not really considered an inva- sive species, for the simple reason that many biologists in the field of invasive species feel that the term is reserved only for those that are non-native. | have always had a problem with that philosophy, especially when we see our native red cedar populate once arable and fertile agricultural fields in South Marysburgh. To me, that is invasive. Anything native can be cessfully reaches our flower beds. Eat field experience. | though is how the word is used, whether as an adjective or as a noun. A plant can be invasive, but not necessarily “an invasive”. The fall webworm caterpillar that we are seeing right now, does not develop into something as glamorous and profound like the lowly tomato hornworm that becomes a gorgeous sphinx moth. The fall webworm caterpillar evolves into a drab fall webworm moth, a rather nondescript white moth—almost pure white in northern parts of the province, but assuming a more mottled look the farther south we go. No doubt, you Fall Webworm_Photo by Keith Douce have seen these moths, and not realized the connection be- tween them and the caterpillar we are seeing now. Like so many other of our local insects, they overwinter here in the pupal stage behind bark or under leaf litter. Pry back a piece of loose bark sometime and you may find the thin brownish cocoon, made of silk and interwoven with the detritus of dead insect parts, leaves and organic material. e sure way of distinguishing fall webworm nests from those of tent caterpil- lars, other than the time of the year, is their placement in the trees. Look at the webbed nests we are seeing right now; they are placed near the very ends of branches, the leaves webbed together with silk. Tent caterpillars in the spring place their webbed nests far- ther back in the branches. Using modified salivary glands along the sides of their mouth, caterpillars can produce silk as needed. It is within this webbing where the caterpillars eat, relatively safe from any bird predators looking for a quick meal, expanding the webbing as needed to cover fresh crops of leaves. Still, there are many predators and parasites that are out looking for them, like the social wasps, predato- ry stink bugs and parasitic flies and wasps. These natural enemies help maintain webworm populations and although their numbers do periodically crest into outbreaks, any so- called damage they do is mainly cosmetic. In general, the defoliation won’t hurt the tree because the damage is usually localized to just a few branches and since it occurs later in the season, the tree has already had time to store food. Also, because webworms are among the most polyphagous of insects, feeding on just about any kind of tree, the damage they do is not as serious as it might be from tent caterpillars which are a bit more fastidious in their menu choices. We always seem to have this annoying obsession on wanting to fix things—to have order in our lives and to “manage” nature. Nature did very well by itself before we came along. The webs will eventually weather away over the winter. In short, fall webworms really are not a big deal. Just unsightly. Fall Webworm Mouth_ Photo by Terry Sprague is a professional field naturalist who lives on Big Island. His website on nature in the County can be found at www.naturestuff.net and he can be reached at tsprague@xplornet.com Terry and Christie—