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Weevils are a type of beetle with mouths at the end of a sometimes very long head. They’re an important group of insects to be familiar with – most feed on plant material, and many are considered to be economic pests. The largest weevil in North America is the palmetto weevil (Rhynchophorus cruentatus), which is native to the US and attacks stressed and dying palm trees.Palmetto weevil adults are large – about ¾ to 1¼ inches long – and vary in color from solid black to almost completely red with a variable black pattern. The larvae, or “grubs,” are legless and a creamy to yellowish color. They have dark brown heads and are very hard. Mature larvae can be large as well, measuring over an inch long with a mass of close to a quarter of an ounce! Eggs are laid in the bases of leaves of stressed or dying palm trees. After hatching, larvae feed on the plant’s stem tissue. Mature grubs move to the outside of the stem and make a cocoon from palm fibers. Adults emerge from the cocoon and live for several weeks on or near palm trees. Symptoms of palmetto weevil infestation usually involve an initial decline of younger leaves. As the infestation progresses, larval feeding damage and secondary rot can weaken the tree enough that the top falls over. This condition is called “popped neck.” Early detection of weevil infestation is difficult, and insecticidal treatment – even in the early stages of infestation – is futile. The best management tactic is to cut down infested palms and destroy them before adults emerge from the tree and lay more eggs.
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