Phyllonorycter ledella

Phyllonorycter ledella (Walsingham, 1889)

(Figs. 40–42)

Lithocolletis ledella Walsingham 1889: 79. Phyllonorycter ledella (Walsingham) — Davis 1983: 10.

Leaf mine. An upper-surface blotch, becoming wrinkled when mature (Figs. 40–41).

Hosts. Ericaceae: Rhododendron columbianum (Piper) Harmaja, R. groenlandicum (Oeder) Kron & Judd.

Distribution. Canada: AB, BC, NB, ON, QC, SK, YT; USA: CA, ME, MI; Greenland.

Review. Walsingham (1889) reared the type series from “somewhat folded mines, occupying the whole upper side of leaves of Ledum glandulosum ” (= Rhododendron columbianum) collected in Mendocino Co., California. This species has since been recorded from Quebec and Greenland, where it has been reared from Rhododendron groenlandicum (Handfield 1997; Karsholt et al. 2015; De Prins & De Prins 2019), as well as from British Columbia (Pohl et al. 2015), Yukon, Alberta, and Ontario (Pohl et al. 2018). An aborted mine on R. groenlandicum apparently representing Phyllonorycter ledella was photographed in Saskatchewan (Dombroskie 2017), and Adam (2019) reared adults from this host in New Brunswick (Fredericton, York Co.). Karsholt et al. (2015) stated that the distribution of P. ledella includes “north-eastern and western USA,” but apart from Michigan specimens listed in Appendix 1 of Landry et al. (2013), there are no specific literature records from states other than California. CSE has found old mines on R. groenlandicum in Maine (Steuben, Washington Co.; Figs. 40–41).

Comments. In Greenland it has been suggested that Phyllonorycter ledella may have a two-year life cycle, with larvae hibernating in non-deciduous leaves (Karsholt et al. 2015). Adults have been found in Greenland from late July to early August. The available records from Canada and the US similarly only account for one generation: Dombroskie (2011) photographed what appears to be a mine containing a feeding larva of P. ledella in Ontario on 8 May; the Quebec specimen shown by De Prins & De Prins (2019) was reared from a larva or pupa collected on 10 May (the adult emerged on 29 May according to J.-F. Landry, in litt.); the New Brunswick specimens emerged from 15 to 18 June from mines collected on 22 May (Adam 2019); and the type series emerged in June from mines collected in the same month (Walsingham 1889).