Amauromyza flavifrons (Meigen, 1830)
The mines can be confused with two non-agromyzid leaf miners of the genus Pegomyia (Anthomyiidae) living on the same host plants. The larvae and mines are generally larger and the eggs are not injected into the plant tissue but glued on the surface of the leaf. For distinction of Amauromyza and Pegomyia the initial part of the mines should be checked for external egg remnants whose presence immediately identify Pegomyia spp. being responsible for the mine.
Wing length: 1.9 - 2.7 mm. The species is rather small and has yellow frons but dark third antennal segments and entirely dark legs.
Hypandrium short, 'u'-shaped without apodeme, hypandrial frame rather thin. Epandrium from side view with characteristic shape, without articulated inner parts (surstyli). Ejaculatory apodeme very large, with bowl shaped base, typical for the whole genus. Basiphallus with wide strongly asymmetrical side-arms. Distiphallus black and strong with short basal appendix; terminal tubules clearly separated.
Larval mouth hooks distinctly alternating, right mandible higher than left. Posterior spiracles with three terminal bulbs, the last bulb elongated.
The older larvae create a blotch mine on the upper or lower surface of the leaf. The same larva can also change from one leaf side to the other. Pupation takes place externally. Normally there are two generations per year (Hering, 1949, Spencer, 1973).
Although the females regularly oviposit in Chenopodiaceae leaves, the main host plants clearly belong to the Caryophyllaceae. Scheffer, 1999 a found a significant higher mortality of first instar larvae on Beta than on the caryophyllacean plant Saponaria officinalis.
Several genera of Caryophyllaceae, of these Dianthus (carnation) and Saponaria (see above). Also on two cultivated Chenopodiaceae Beta vulgaris (beet, sugar beet, silver beet, mangold among others) and Spinacia oleracea (Spinach).
Apparently widespread in the Palaearctic region (Spencer, 1976 b); North America: Canada (Ontario), USA (Spencer and Steyskal, 1986).
Amauromyza flavifrons regularly occurs on the Chenopodiacean hosts Beta vulgaris and Spinacia oleracea. Additionally they are reported from cultivated carnations and other Caryophyllaceae. As far as known the larvae cause only little damage to their host plants because their population density is low.
On Beta also two more serious leaf miners of the fly genus Pegomyia (Anthomyiidae) regularly occur. Their younger mines can be easily confused with those of Amauromyza flavifrons (see above). Therefore sometimes the actual population of the agromyzid leaf miner may have been over- or underestimated.
The current results by Scheffer (see bionomics) indicate a possible evolution towards an increased suitability of the Chenopodiacean host plants (but see the discussion in Scheffer, 1999 b).