Erebia christi Rätzer, 1890

Host plants:
Festuca grasses (F. ovina agg.)

Habitat:
Erebia christi inhabits dry, sunny, steep, rocky cliffs between about 1350 and 2300m that are most often interspersed with a few Larix trees.

Life cycle:
The butterflies occur mostly between late June and mid-July. In uneven years population density is said to be higher. In cool years or in the uppermost sites the flight time may be later, more in mid- to late July as in 2200 m in 2024. The adults usually keep themselves in the cliffs, but both genders occasionally come down to adjacent flower-rich grasslands to feed. A common nectar plant is Thymus. The eggs are attached singly to plant parts (often dead grass leaves or old Larix needles) in the lower part of Festuca tussocks most often directly above rock.

The larvae hibernate twice, first mostly in L1 instar, then again in L3 (which is the penultimate instar). According to year and altitude the first hibernation may also take place sometimes as L2. For hibernation the larvae withdraw deep into the tussocks. They are mature usually in May and pupate also within the Festuca tussocks between a loose, faint webbing. Contrary to many other Erebia which pupae often rest head-up, a E. christi pupa has been observed head-down.

Endangerment factors:
In many cliffs Erebia christi appears relatively safe in concern of direct habitat destroyment by man. But especially in lower altitudes road construction already destroyed good habitats in earlier years. Scrub and tree encroachment (Larix and others) may affect less extreme habitats and lead to habitat loss. Finally, global warming may lead to summer drought and deteriorating habitat quality and especially in low altitudes also to development problems by higher temperatures (diapase stage, synchronization etc.).

Remarks:
Erebia christi is endemic to the southern side of Simplon pass and known only from a few sites in Switzerland and adjacing Italy.

Hints on determination:
The uppermost redbrown spot on forewing upperside bears usually a black spot. This is very unusual in similar species. But occasionally (especially in males) this uppermost black dot may be faint or even missing.