Melanagromyza Hendel 1920

Melanagromyza sp. 2

Material examined. OKLAHOMA: Payne Co., Mehan, 36.013839°, -96.998103°, 12.vii.2017, em. ~ 10.iv.2018, M.W. Palmer, ex Lactuca canadensis, # CSE4452, CNC1135642 (1♀).

Host. Asteraceae: Lactuca canadensis L.

Larval biology. Probably an internal stem borer (see Comments).

Puparium. Formed within the stem.

Phenology and voltinism. This species is evidently univoltine, given that the adult emerged in spring from a stem collected the previous July.

Comments. The only previous record of a Melanagromyza from Lactuca is that of several M. splendida Frick paratypes from Hawaii, listed as “reared from larvae mining lettuce leaves” (Frick 1953)—which should not be construed as representing true leafmining since as far as is known M. splendida feeds as a borer in the stem or in the midrib of large leaves (Spencer 1973). Unlike M. splendida, the Oklahoma female has closely spaced fronto-orbitals (the anterior pair is not anteriorly displaced) and the wing is approximately 3.2 mm (not 1.9–2.6 mm). The female emerged from a bulk sample of mined stems, with the mines terminating in conspicuous gall-like “scabs” of stem tissue and dried latex, inside which the puparia were formed. We are reasonably sure that these external symptoms were in fact caused by an undetermined Ophiomyia species, and we presume that the Melanagromyza larva fed and pupated in the pith of a stem.