Agromyza ambrosivora Spencer

Eiseman, Charles S. & Lonsdale, Owen, 2018, New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species, Zootaxa 4479 (1), pp. 1-156 : 7-8

Agromyza ambrosivora Spencer

( Fig. 64 )

Material examined. COLORADO: Chaffee Co., Poncha Springs , South Arkansas River, 8.vii.2015, em . 28.vii– 1.viii.2015, C.S. Eiseman, ex Helianthus annuus , #CSE1872, CNC654328–654332 (1♂ 4♀); MASSACHUSETTS: Worcester Co., Sturbridge, Leadmine Rd. , 6.vii.2013, em . 20.vii.2013, C.S. Eiseman, ex Ambrosia artemisiifolia , #CSE725, CNC392679 , CNC392680 (2♀); PENNSYLVANIA: Chester Co., Pottstown , Warwick County Park , 10.viii.2014, em . 2.ix.2014, N. D. Charney, ex Ambrosia trifida , #CSE1371, CNC384846 (1♂).

Hosts. Asteraceae : Ambrosia artemisiifolia L., A. * trifida L., * Helianthus annuus L. Some specimens from Los Angeles and Ventura Counties, California, were caught at sites where Artemisia douglasiana Besser was one of the dominant plants, and Spencer (1981) stated that it therefore seems probable that this was the host. He noted that Ambrosia is not known in these counties, but the genus is now known from both counties and several Helianthus species are also present (USDA, NRCS 2017).

Leaf mine. ( Fig. 64 ) On Ambrosia artemisiifolia , “several larvae frequently feeding together to form a blackish leaf-mine, which extends from the apex of the pinnately divided leaves towards the midrib” ( Spencer 1969). In our example the apices of three lobes were disfigured by the mine. The mine on A. trifida was a brown blotch in the angle between the midrib and a lateral vein; there was a narrow initial linear portion that had been mostly obliterated. The mines on Helianthus ( Fig. 64 ) began near the leaf margin in the basal half of the leaf blade and followed the margin apically, widening gradually.

Puparium. Brown; formed outside the mine.

Distribution. USA: CA, *CO, *MA, MD ( Scheffer et al. 2007), NY ( Scheffer & Lonsdale 2018), *PA; Canada: ON.

Figures

FIGURES 63–74. leaf mines; 63: Agromyza albitarsis Meigen in Populus balsamifera; 64: A. ambrosivora Spencer in Helianthus annuus; 65: A. aristata Malloch in Ulmus rubra; 66: A. bispinata Spencer in Elymus hystrix; 67: A. diversa Johnson in Laportea canadensis; 68: A. fission spec. nov. in Celtis occidentalis; 69: A. idaeiana Hardy in Geum macrophyllum; 70: A. isolata Malloch in Populus balsamifera, young mines (left) with probable A albitarsis mine at leaf margin; 71: same Populus balsamifera leaf with completed mines, A. isolata to left of midrib and probable A. albitarsis to right; 72: A. parca Spencer in Dichanthelium clandestinum; 73: A. pseudoreptans Nowakowski in Urtica dioica; 74: A. pudica in Dichanthelium scoparium.