The larvae, or grubs, are legless and range in color from creamy to yellowish. Their distinctive head is dark brown and extremely firm. They have enormous mandibles. Mature larvae can grow to be fairly large, weighing up to six grams. While we are not aware of any human ingestion of palmetto weevils in the United States, palm weevil larvae are considered a delicacy in other parts of the world.
Palmetto weevil adults range in hue from full black to almost red with a varied black pattern. Their total length ranges from 1.9 to 3.0 cm from the tip of the rostrum to the end of the pygidium (the tergum of the final visible segment of the abdomen). The surface of the rostrum distinguishes adult males and females. Male rostra are rather straight and covered with microscopic bumps, but female rostra are ventrally bent, tapering, and smooth.
Host plants:
Palmetto weevil is closely related to cabbage palmetto Loddiges ex J.A. et Schultes. Other palms, mostly imported species, have suffered larval infestations. Potential hosts include the Canary Island date palm, the Bismarck palm, and the latan (Latania spp.) palm.
Territory:
The palmetto weevil is native to Florida and until recently was the only species of palm weevil in the continental United States.
Damage caused by Palmetto Weevil:
Palmetto infection symptoms are similar to an oak tree dying from an oak or pine infestation. Although the amount and ratios of volatile chemicals emitted by damaged trees are unclear, many have been discovered to be appealing. Furthermore, male weevils create and emit an aggregation pheromone (5-methyl-4-octanol, or “cruentol”) that attracts other male and female weevil species. Mating and egg-laying occur once a population has assembled on the tree.
Life history and Habits:
The palmetto weevil has a full life cycle, beginning with an egg and progressing through numerous larval instars, prepupal, pupal, and adult stages. Eggs are placed at the bases of leaves or wounds on the host palm. In her lifetime, a female will lay an average of 207 eggs. The larvae’s hunger grows as they molt (grow and lose their cuticle), and they prefer to eat in the soft tissue around the apical meristem. Mature grubs travel to the stem or petioles’ perimeter and spin a cocoon out of palm fibers. The larvae undergo a prepupal stage after wrapping themselves in the cocoon, followed by a pupal stage. Adults can survive for several weeks to months if moisture is provided.
