Insects & Other Arthropods
Ficus Leaf-Rolling Psyllid Introduced in Southern California
This aphidlike insect (Trioza brevigenae, family Psyllidae) is native to India and was inadvertently introduced into Southern California in about 2016. It occurs on Indian laurel fig, Ficus microcarpa, in at least the counties of Los Angeles, Orange, Riverside, San Bernardino, San Diego, and Ventura.
Adults are about 1/8 inch long with a pale brownish-green head and thorax and red eyes. The abdomen is green when adults are young then turns brown as adults age. Wings are transparent with no coloration and at rest are held tentlike over the body. At rest on the leaves, adults hold the abdomen raised at about a 45-degree angle. Adults can commonly be observed to wag their abdomens repeatedly from side to side.
Where young nymphs settle to feed, an oval, shallow pit develops in the leaf surface. As feeding continues infested leaves become tightly rolled. Older nymphs are mobile and have a brownish-green, elongate, oval body. Late instars are up to 1/10 inch long and have long, white, waxy filaments at the front and rear ends. Wing pads become visible in late instars.
The lengthwise rolling of leaves caused by ficus leaf-rolling psyllid differs from the loose curling or folding of leaves caused by Cuban laurel thrips, Gynaikothrips ficorum, and weeping fig thrips (PDF), Gynaikothrips uzeli. These other galling insects also cause brown, reddish, or purple scars on the damaged leaves; in comparison leaves remain uniformly green when galled by ficus leaf-rolling psyllid. Abundant leaf gall wasps, Josephiella microcarpae, can also cause curled or distorted leaves, but this insect's leaf deformations are distinctly rounded and swollen. When ficus eye-spot midge is the cause of green swellings in leaves, these galls turn brown after the midge larvae exit the leaf to pupate.
Certain caterpillars, spiders, and other arthropods can also roll leaves. Open rolled leaves to reveal the arthropods themselves to reliably distinguish the cause. Note that mealybugs, whiteflies, or other arthropods may also be present in rolled ficus leaves and their feeding can contribute to foliage deformation or discoloration.
Psyllids develop through three life stages: egg, nymph, and adult. Adult females lay eggs on young leaves. After hatching, nymphs sucking feed on foliage and develop through five increasingly larger instars before maturing into winged adults.
Adults and nymphs suck plant sap from leaves of Indian laurel fig. Feeding by nymphs causes infested leaves to become tightly rolled lengthwise into narrow cylinders about 1/6 inch in diameter. These cylinders may harbor various nymphal stages. Infested leaves become dry and brittle but remain green. Feeding by abundant psyllids can cause premature leaf drop and a sparse canopy. Several other insects also cause galling or rolling of ficus leaves; discriminate them as described above in "Identification."
Whether control action is warranted to protect the health of Indian laurel fig is unknown. There apparently is no research-based information on managing this pest that otherwise is known only from India. Green lacewings, lady beetles, and minute pirate bugs feed on the psyllid, but whether natural enemies can potentially provide biological control is unknown.
Regularly inspecting succulent, young leaves of Indian laurel fig and removing psyllid-infested leaves and bagging them for disposal can potentially reduce the pest's abundance and spread. Contact insecticides may not be effective because the psyllid feeds protected within leaf rolls. Applying systemic insecticide (e.g., acephate, imidacloprid) when new growth first appears may reduce the extent of subsequent leaf damage.
For more information and photographs see Ficus Leaf-rolling Psyllid, Trioza brevigenae: A New Pest of Ficus microcarpa in Southern California and New Pests of Landscape Ficus in California (PDF).