common name: blotch leafminer
scientific name: Amauromyza maculosa (Malloch) (Insecta: Diptera: Agromyzidae)
Introduction - Synonymy - Distribution - Identification - Hosts - Leaf Damage - Management - Selected References
A blotch leafminer, Amauromyza maculosa (Malloch), is a pest of dooryard plantings of chrysanthemum throughout most of Florida. It is not an important pest of commercial chrysanthemums in the principal commercial planting areas of Bradenton-Ft. Myers and Stuart-Delray Beach. This species, which, according to Spencer and Stegmaier (1973), probably evolved in South America and has extended its range into North America since the end of the Pleistocene Period, may be distinguished readily from related species by the variegated color of the halteres of the adult flies. The large blotch mines, produced on foliage by the feeding of the larvae, are similar to those produced by larvae of another agromyzid fly, Nemorimyza posticata (Meigen), which also occurs in Florida and usually on Solidago and Aster.
Figure 1. Foliar damage caused by the blotch leafminer, Amauromyza maculosa (Malloch), showing leaf with mines and oviposition punctures. Photograph by Division of Plant Industry.
Agromyza maculosa Malloch, 1913: 302. Holotype female from Jamaica, New York, in U.S. National Museum of Natural History.
Phytobia (Amauromyza) maculosa Frick, 1952: 393.
Throughout most of the United States, including Florida and Hawaii; Antilles, Bahamas, Bermuda, Costa Rica, Argentina, Brazil, Uruguay and Venezuela.
The adult is a small, shiny black, clear-winged fly about 2.2 to 2.7 mm long. Head entirely black; mesonotum shining black; pleura and legs entirely black; squamae and fringe silvery white; halteres variegated, primarily white, but knob with a conspicuous black area above; wing length about 2.2 to 2.7 mm. Larvae are yellowish white, about 3 mm long, and make blotch-like tunnels within leaves where these larvae are readily visible as they feed.
Figure 2. Foliar damage caused by the blotch leafminer, Amauromyza maculosa (Malloch), showing leaf with mines and oviposition punctures. Photograph by Division of Plant Industry.
Figure 3. Mature larva of the blotch leafminer, Amauromyza maculosa (Malloch). Photograph by Division of Plant Industry.
Polyphagous on Compositae; known hosts in Florida include Baccharis, Bidens, Chrysanthemum, Emilia, Erechtites, Eupatorium, Gaillardia, Gnaphalium, Helianthus, Melanthera, Senecio, Sonchus, and Tagetes. Recorded hosts elsewhere include Arctium, Artemisia, Aster, Erigeron, Lactuca, and Xanthium.
Feeding larvae cause conspicuous blotch mines in foliage before they emerge and pupate externally. Injury to foliage by mines and oviposition punctures causes plant to be unsightly. Heavy infestations may cause some leaf mortality. Three to six larvae are common in a single leaf, frequently forming a large community mine.
Figure 4. Chrysanthemum plant severely infested by the blotch leafminer, Amauromyza maculosa (Malloch). Photograph by Division of Plant Industry.
Figure 5. Blotch mine in chrysanthemum leaf opened to expose the feeding larva of the blotch leafminer, Amauromyza maculosa (Malloch). Photograph by Division of Plant Industry.
Figure 6. Oviposition punctures in chrysanthemum leaf caused by the blotch leafminer, Amauromyza maculosa (Malloch). Photograph by Division of Plant Industry.
Pest management programs for commercial production of chrysanthemums are sufficient to control A. maculosa.
- Frick KE. 1952. A generic revision of the family Agromyzidae (Diptera) with a catalogue of New World species. California University Publication Entomological 8: 339-452.
- Frick KE. 1959. Synopsis of the species of agromyzid leafminers described from North America (Diptera). Proceedings of the U.S. Natural History Museum 108: 347-465.
- Frost SW. 1924. A study of the leaf-mining Diptera of North America. New York (Cornell) Agricultural Experiment Station 78: 1-228.
- Malloch JR. 1913. A revision of the species in Agromyza Fallén, and Cerodontha Rondani (Diptera). Annals of the Entomological Society of America 6: 269-336.
- Mizell RF, Fasulo TR, Short DE. (2002). WoodyBug: pest and beneficial arthropods of southeastern U.S. woody ornamentals. University of Florida/IFAS. CD-ROM. SW 119.
- Spencer KA, Stegmaier CE Jr. 1973. Agromyzidae of Florida with a supplement of species from the Caribbean. Arthropods of Florida and neighboring land areas 7: 1-205.
- Stegmaier CE Jr. 1967. Some new host plant records and parasites of Phytobia (Amauromyza) maculosa in Florida (Diptera: Agromyzidae). Florida Entomologist 50: 99-101.
- Stone A. et al. 1965. A Catalogue of the Diptera of America North of Mexico. USDA Agricultural Handbook No. 276. 1696 p.
- Waters WE, Conover CA. 1969. Chrysanthemum production in Florida. University of Florida Agricultural Experiment Station Bulletin 730: 1-64.