As autumn arrives, you may notice small webs starting to appear on the tips of your oak tree's branches. Are you wondering how to get rid of these webworms on a live oak tree (Quercus virginiana, USDA zones 8-10)? Fortunately, getting rid of webworms and the associated webs is not a very complicated process.
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Can Webworms Harm the Tree?
Webworms are the caterpillar form of a small white moth native to North America. Webworms make these webs in your trees as they eat, forming a nest around themselves. This permits them to eat the leaves of your trees while staying safe from predators. The webbed nests start to form in late summer when the webworms hatch and will grow in size as the webworms search for more leaves. After about six weeks, most of the worms leave the tree to pupate elsewhere.
While you may notice the webs on an oak tree, webworms can infest any deciduous tree, from oak trees to fruit trees. Since webworms are so common and nearly any deciduous tree can be susceptible, it is a relief to know that the worst thing webworms can do to a tree is to eat through most of the leaves, leaving behind large swaths of webs. Some webs can reach up to 3 feet in length, and they can be quite unsightly, containing partially eaten leaves, droppings and visible webworms.
Established trees can withstand losing a considerable amount of foliage, and most injuries done to the tree by webworms is cosmetic. There is no risk of the webworms or their nests damaging or killing the branches, so the tree should have no problem producing new foliage come springtime. Young trees, however, could suffer complete defoliation if the infestation is allowed to continue. In this case, interference may be necessary.
Removing Webworms From Trees
Webworm removal is as simple as poking the webs with a stick. Using a rake or anything long enough to reach the impacted area, break open the webs. Doing this will expose the webworms to their natural predators, and they should take care of the infestation for you. You could also choose to pull down the webs and destroy the webworms yourself or simply prune the affected branches.
Some experts recommend using Bt, a bacterium that will not harm plants, people or pets. However, it will kill all caterpillars of potentially wanted butterflies, not just webworms. If you are looking for an organic insecticide, neem is an option. Like Bt, neem won't harm people or pets, but it will kill many beneficial insects as well, and it can harm certain plants. If you choose to use an insecticide, be sure to tear open the webbed nests so the insecticide reaches the webworms.