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Azalea Leafminer, Caloptilia azaleella (Brants) (Insecta: Lepidoptera: Gracillariidae)1
G. W. Dekle2Introduction
The azalea leafminer, Caloptilia azaleella (Brants), is a larva of a tiny purple- and yellow-marked moth. It is found in Florida wherever azaleas are grown. FDACS/ Division of Plant Industry records reveal that larvae have been collected in Florida in every month of the year. However, infestations are most noticeable in nurseries from early spring through August. Leaf injury by the larva is very characteristic. The folding over of the leaf tip or leaf margin occurs after the larva emerges from within the leaf.
CREDITS: Russell F. Mizell, University of Florida
Figure 1. Mature larva of the azalea leafminer, Caloptilia azaleella (Brants). Distribution
This insect is a destructive pest of azaleas throughout the range of the host. The insect is found from Florida to Texas and north to Long Island, New York, West Virginia and the Ohio Valley. It is also found in northern California and the U.S. Pacific Northwest (Johnson and Lyon 1994, Heppner 2003).Description and Biology
The adult azalea leafminer deposits eggs on the underside of the leaf along the midrib. When mature, the larva often selects an undamaged leaf, rolls up in it and pupates. The adult moth emerges in about a week, mates and begins the cycle again (Johnson and Lyon 1994).
CREDITS: Russell F. Mizell, University of Florida
Figure 2. Egg of the azalea leafminer, Caloptilia azaleella (Brants).
CREDITS: Russell F. Mizell, University of Florida
Figure 3. Pupa (pupal case removed) of the azalea leafminer, Caloptilia azaleella (Brants). The azalea leafminer is a leafminer only for the first half of its larval life. Upon hatching, the young larva enters the leaf directly beneath its eggshell and feeds as a leafminer, creating a blister on the underside of the leaf. The mined area turns brown (Johnson and Lyon 1994).
CREDITS: Division of Plant Industry
Figure 4. Young larva (white area) of the azalea leafminer, Caloptilia azaleella (Brants). Note brown color of mined area. Once it has reached mid-sized, the larva migrates to the upper leaf surface and by means of silk pulls the leaf over its body and chew holes in the leaf. The larva may also tie newly expanding leaves together at the tip of a shoot and feed in the same manner. At this point, the larva is then known as a leaftier. Injured leaves usually turn yellow and drop (Johnson and Lyon 1994).
CREDITS: Russell F. Mizell, University of Florida
Figure 5. Mid-sized larva of the azalea leafminer, Caloptilia azaleella (Brants). Note frass (insect waste) at right of image. Head of larva is at left. The larval stage that folds the leaf is about 0.5 inch long, yellowish, and with three pairs of abdominal prolegs which are found on abdominal segments 3, 4, and 5. The proleg hooks (crochets) are singly arranged in a U-shaped pattern (penellipse), with a series of crochets within the penellipse.
CREDITS: Division of Plant Industry
Figure 6. Larva with abdominal segments bearing prolegs indicated by number.
Figure 7. Ventral view of left proleg, fourth abdominal segment, showing arrangement of crochets. The adult is a small, yellow or golden-colored moth with purplish markings on the wings. The wingspread is about 10 to 13 mm. Most of its life is spent hidden among the leaves of the host.
CREDITS: Russell F. Mizell, University of Florida
Figure 8. Adult azalea leafminer, Caloptilia azaleella (Brants), at lower right. Note azalea leaf damage in background.
CREDITS: Russell F. Mizell, University of Florida
Figure 9. Ovipositor of adult female azalea leafminer, Caloptilia azaleella (Brants). In Florida, there is continuous breeding. Georgia has reported three to four generations a year, while even as far north as Long Island there are two generations per year. In Oregon, there are three generations per year and the insect overwinters as a last-instar larva or pupa in a rolled leaf, or occasionally as a tiny miner in a leaf (Johnson and Lyon 1994).
Hosts
Azaleas (Rhodendron spp.) are the only hosts recorded for this insect.Economic Importance
This leaf miner is a pest of container and field-grown azalea nursery stock. However, plants in the landscape are also commonly attacked. Injured leaves usually turn yellow and drop, thus causing an unsightly plant. If the insect is controlled early, the plants will outgrow the injury it causes (Johnson and Lyon 1994).
CREDITS: Division of Plant Industry
Figure 10. Under leaf surface of azalea foliage damaged by azalea leafminer, Caloptilia azaleella (Brants). Early instar injury (straight arrows), late instar injury (curved arrows).
CREDITS: Division of Plant Industry
Figure 11. Upper leaf surface of azalea foliage damaged by azalea leafminer, Caloptilia azaleella (Brants). Management
Cultural Control
Prune off and destroy infested branches. Keep plants healthy (properly irrigated and fertilized) so they can tolerate and outgrow the damage (Buss 2006).Biological Control
There are at least three different species of parasitoids of the azalea leafminer of the genus Sympiesis Förster (Hymenoptera: Eulophidae). They are the major species attacking the pupa (Mizell and Schiffhaur 1991).
CREDITS: Russell F. Mizell, University of Florida
Figure 12. Larva of a Sympiesis sp. parasitoid feeeding on a larva of an azalea leafminer, Caloptilia azaleella (Brants). Chenical Control
Leafminers are difficult to control as they are protected by leaf tissue. The best time to manage them is when larvae first hatch inside the leaves and begin to feed as plant damage is minimal. When many large or long mines are seen, the leafminer may have completed its development, and control is not useful (Buss 2006).For more information see the Insect Management Guide for Leafminers on Ornamental Plants.
Acknowledgements
The Project Coordinator thanks Dr. Russell F. Mizell, University of Florida, for his review of this updated publication and correcting the captions used on his color images.Selected References
Burks RA. (2003). Sympiesis Förster, 1856. Key to the Nearctic genera of Eulophidae, subfamilies: Entedoninae, Euderinae, and Eulophinae (Hymenoptera: Chalcidoidea). http://www.faculty.ucr.edu/~heraty/Eulophidae/Sympiesis_page.html (20 March 2007).Buss EA. (2006). Leafminers on Ornamental Plants. EDIS. http://edis.ifas.ufl.edu/MG006 (20 March 2007).
Heppner JB. 2003. Lepidoptera of Florida. Arthropods of Florida and Neighboring Land Areas Vol. 17. Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL.
Kerr TW. 1959. Insects of ornamental trees and shrubs in Rhode Island. Agricultural Experiment Station Bulletin 348: 12-13.
Dickey RD. 1965. Azalea culture. Agricultural Experiment Station Circular S-172. University of Florida, Gainesville, Florida.
Johnson WT, Lyon HH. 1994. Insects That Feed on Trees and Shrubs. 2nd ed. rev. Cornell University Press, Ithaca, NY. 560 p.
Mizell RF, Schiffhaur DE. 1991. Biology, effects on hosts, and control of azalea leafminer (Lepidoptera: Gracillariidae) on nursery stock. Environmental Entomology 20: 597-602.
Footnotes
1. This document is EENY-379 (IN736) (originally published as DPI Entomology Circular 55), one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: June 2007. This document is also available on Featured Creatures Website at http://creatures.ifas.ufl.edu. Please visit the EDIS Website at http://edis.ifas.ufl.edu.2. G.W. Dekle (retired), Florida Department of Agriculture and Consumer Services, Division of Plant Industry.
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