Plumeria Worms

Whether you refer to it as plumeria (Plumeria rubra) or frangipani, this beautifully scented tree displays five-petaled blossoms in a variety of colors, such as red, pink or yellow, that add immense interest to your landscape. However, what may evoke a bit of fear while swiftly damaging your plumeria trees is a pest referred to as a worm that is actually a large caterpillar.

Giving your plumeria tree the regular, required care it needs prepares this deciduous plant to avoid and heal from problems, such as pest infestations. Grow plumerias in areas of the home garden that provide full sun; however, this tree will continue to grow in partial shade. For best growth, maintain well-drained soil with a slightly acid pH level. Plumerias tolerate drought but need irrigation during extended periods of dryness. Grow plumeria trees in U.S. Department of Agriculture plant hardiness zones 10b through 11.

A pest referred to by a wide variety of names, including tetrio sphinx, giant gray sphinx and frangipani hornworm, attacks plumeria plants. In its adult form this bug is a gray moth with brown and white markings. The moth's wingspan measures up to approximately 5-1/2 inches across. Moths lay up to 100 eggs on a single tree. Hatched larvae, referred to as worms or caterpillars, grow to lengths of up to 6 inches while displaying vividly marked bodies in a velvet-textured black color with yellow horizontal stripes and an orange head.

Because of the amount of eggs laid on a single tree and the fact that one caterpillar can eat up to three big leaves on a daily basis, according to the University of Florida Extension, an infestation of frangipani hornworms can result in severe tree damage. Eating both leaves and occasionally twigs, these pests may lead to defoliation in as short a time as three days. Look for these pests during the warmer months.

Because the caterpillar's toxic hairs can cause irritation, practice extreme caution around these pests. If you are pregnant or nursing, seek assistance and avoid contact. Always wear protective gardening gloves and clothing when dealing with pests. These pests can be removed by hand from the plumeria tree and destroyed, particularly when they are still young and small. While they can defoliate a tree, the damage is typically not severe enough to warrant the use of chemical insecticides. However, you may manage them with the microbial insecticide Bacillus thuringiensis (Bt). Apply according to the directions on the product label, which may instruct you to apply Bt at a rate of 4 teaspoons per 1 gallon of water. Use a sprayer and thoroughly cover the affected plant, reapplying once a week until the problem is under control.