Colias myrmidone (Esper, [1781])

Host plants:
The larvae feed on Chamaecytisus species such as Ch. ratisbonensis or Ch. rhutenicus.

Habitat:
Colias myrmidone inhabits sunny, warm and rather dry forest steppes in the lowlands below 800m. These are most often grazed, nutrient-poor grassland slopes (but also plain areas) with varying portion of groves or smaller or larger woodlands. Because mico-climate is very important for successful larval development, it is necessary that the habitats are grazed neither too intense (damaged host plants) nor too little (felting of the vegetation). Also the portion of woods plays a role.

Life cycle:
The adults usually occur in two generations between mid-May and June and again between mid-July and mid-September. In September there is sometimes (in warm years and/or warm places) a very partial third generation. The eggs are deposited singly on the host plants. The still small larva (L3) hibernates. In early May 2021 as well still small (L3) and mature larvae have been recorded near Cluij-Napoca in Romania, according to exposition and micro-climate. The larvae are well camouflaged on the shoots of the larval host plants which are sought-after also by other Lepidoptera larvae. Accompanying species were many larvae of Gynaephora fascelina, Rhyparia purpurata and singly Orgyia recens and various Noctuidae (e.g. Aporophyla sp.). Pupation occurs as belted pupa in the grass- or mosslayer within a cavity that is constructed with loose silken webbing.

Remarks:
Colias myrmidone is threatened with extinction in almost all of its European range, or has already disappeared totally as it is the case in Germany, the Czech Republic and Austria. Today, it is still found in small and very isolated relic populations from northeastern Poland, Slovakia and Romania eastwards across Russia to the regions east of the Urals in western Sibiria. Especially in the western part the remaining populations may become extinct one after the other in future. Reasons are the increasing eutrophication and intense agricultural management of the landscape, the densening and darkening of forme steppe woodlands and may-be also climate change. In the remaining populations isolation and also suboptimal management (with subsequent loss in extent and quality of larval habitat) work towards weakening and finally extinction. However, proper natura 2000 management plans may locally prolongate extinction or even stabilize some populations of this European protected species - so is the hope. Both too intensive and too extensive grazing will push back Colias myrmidone.