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Despite mass movements of insects being documented for decades, whether dragonflies migrate in Europe has not yet been experimentally tested. Similarly, little is known about the influence of weather on the movement decisions and intensity of dragonflies. Taking advantage of large movements of dragonflies along the Baltic Sea coast of Latvia, we investigated whether European dragonflies showed directed movements indicative of migratory behaviour and how weather influences their movements. First, we performed orientation tests with individual dragonflies of two commonly captured species,AeshnamixtaandSympetrumvulgatum, to determine whether dragonflies showed directed flight and whether flight direction differed from wind direction. BothA.mixtaandS.vulgatumdisplayed a uniform mean southward orientation, which differed from the prevailing overhead wind direction, indicating migratory behaviour. Second, we investigated the influence of weather conditions on the abundance of dragonflies captured. Differences in flight behaviour in relation to weather conditions were observed betweenA.mixtaand the two smallerSympetrumspecies (S.vulgatumandS.sanguineum). Generally, temperature, cloud cover and wind direction were the most important predictors for dragonfly abundance, with temperature positively, and cloud cover negatively, influencing abundance.Aeshna mixtaappeared to select favourable tail winds (northerlies), whereas abundance ofSympetrumincreased with more easterly winds. Our results provide important information on the influence of local weather conditions on the flight behaviour of dragonflies, as well as evidence of dragonfly migration along the Baltic coast.

A survey of Odonata in streams on Mount Edough, Algeria, and in Kroumiria, Tunisia, indicated strong faunistic similarities between these two areas, characterized by the presence of lotic dragonfly species with protracted larval development such as Aeshna cyanea, Boyeria irene and Onychogomphus uncatus. Climatic oscillations and marine transgressions have isolated these mountains and their North African populations in the past geological times, which have led to distinct adaptations and stenotopy in various zoological and botanical groups. These mountain forests are also a refuge for aestivating Odonata with postponed reproductive maturation like Lestes numidicus, a species new for Tunisia, Lestes barbarus, Sympecma fusca, Aeshna mixta, Sympetrum meridionale and S. striolatum. In the light of increasing human encroachment, urgent conservation efforts are needed to ensure the perpetuity of these unique habitats in North Africa and their biota.

Anisoptera were monitored or sampled regularly at lowland and nearby upland sites in northeastern Algeria during 1992 and 1993. After emerging in lowlands at about sea level in May and June, adults disappeared from lowlands and were then soon encountered in nearby hills at ca 500-1000 m a.s.l. where they aestivated in woodland for about three and a half months (Sympetrum meridionale) or more than four months (Aeshna mixta, Sympetrum striolatum). During aestivation adults foraged, gradually changed colour and achieved reproductive maturity. Aestivation ended with the onset of heavy rain in late September or early October when mature adults reappeared at lowland sites where they promptly exhibited reproductive behaviour. Although no adults marked in lowlands were recaptured in uplands, the inference that individual adults made two-way flights between lowlands and uplands is compelling. Postponed reproductive maturation in upland refuges maintains continuity of the life cycle in habitats inimical to...