Maggots were found tunneling in stems of lettuce growing in an aquaponics operation. Four small black flies (BL=2.1mm) were reared out and identified as Melanagromyza splendida, AGROMYZIDAE. This fly was first collected on Guam in 1986. According to Schreiner 1991:

“This agromyzid fly is an internal borer in the stems and midribs of large leaves (Spencer 1973). Previously, it was known to attack Compositae and Umbelliferae, but on Guam it has been reared from tomato leaves and from midribs of mizuna, an Asian Brassica variety. The native distribution of this species is tropical and subtropical Americas, but it has been present in Hawaii for many years.”

Ron Mau lists M. splendida as a pest of lettuce in his Knowledge Master website for crop pests in Hawaii, and uses “safflower stemminer” as a common name. According to Spencer 1973:

“This species has been reared from lettuce in Hawaii but significant damage has not been reported.”

References

Schreiner, Ilse H. 1991. Sources of new insects established on Guam in the post World War II period. Micronesica Suppl. 3: 5-13.

Spencer, K. A. 1973. Agromyzidae (Diptera) of economic importance. W. Junk. The Hague. 418 pp. Available online in Google Books.

Label Info

Collection label:

AM20090321.002a,b,c,d
reared from maggots tunneling in lettuce stem
Triton Farm, Yigo, Guam
13.53275N 144.87232E
M. Marutani 21 MAR 2009

Determination label:

AGROMYZIDAE
Melanagromyidae splendida Frick 1953
Det. A. Moore 17 APR 2009

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