Most of the butterflies in Estonia begin their activity in May to June. The exact time when they appear differs by year and depends greatly on the course of spring. So when exactly you can meet Clouded Apollo, Swallowtails, Organge Tip in Estonia?
The family Swallowtails (Papilionidae) is represented in Estonia with three species of which Scarce Swallowtail (Iphiclides podalirius) is a rare and accidental visitor—observers have met it only a few times from late June to mid-July. However, already in May you can encounter specimens of the first generation of the Papilio genus—the only species of the genus in Estonia is the Old World Swallowtail (Papilio machaon). The Old World Swallowtails usually produce a second generation during the summer so that the species can be seen also in July and August; even in September, when the summer has been warm. The third species in the Swallowtails family that is quite abundant here is the Clouded Apollo (Parnassius mnemosyne), the only species of the genus Apollos (Parnassius) found in Estonia. The Clouded Apollo is under protection all over Europe, and, naturally, also in Estonia. The species may be encountered from late May and early June until late July. In Estonia, the species is even divided into three subspecies of which the Parnassius mnemosyne osiliensis that was found in Saaremaa has probably gone extinct. The presumable reason for their extinction is the massive number of odonates (Odonata) in the subspecies’ habitat—the odonates simply ate all the butterflies. Nevertheless, Clouded Apollo is quite common in north-eastern and south-eastern Estonia: if you happen to be in the right place at the right time, you may see tens or hundreds of specimens.
The family Pieridae is represented with 12 species in Estonia. The imagos of the only species in the Black-veined Whites (Aporia) genus—the Black-veined White (Aporia crataegi)—start their activities in mid-June and are active up to mid-July. The genus of Garden Whites (Pieris) is represented in Estonia with three quite common species: Cabbage Butterfly (Pieris brassicae), Small White (Pieris rapae), and Green-veined White (Pieris napi)—all of them appear in May and can be encountered until the autumn. The Bath White (Pontia daplidice) of the genus Whites (Pontia) travels to Estonia; specimens from its first generation have been seen in June and the second generation in July and August. The genus of Orange Tips (Anthocharis) is also represented with one species in Estonia: the Orange Tip (Anthocharis cardamines), which can be seen anywhere in Estonia from mid-May to mid-June. The same applies to the genus of Brimstones (Gonepteryx), who is represented by the Common Brimstone (Gonepteryx rhamni). Since this is an overwintering species we can encounter it already from April until the autumn frosts arrive in September. The genus of Clouded Yellows (Colias) is represented by three species; in Estonia the most common of them is the Moorland Clouded Yellow (Colias palaeno).