Somatochlora alpestris is a Palaearctic dragonfly distributed in cold areas from Europe to the Far East. It is adapted to environments with low mean annual temperatures and short summers. At the upper limit of its altitudinal distribution, conditions for the larvae are particularly unfavourable. Little is known on what and how the larvae prey on during the short summer growth period. To answer this, larvae of S. alpestris were collected in the Central Alps and kept in aquaria until they had egested all their faecal pellets. These were examined under the microscope for remains of prey animals. In addition, various experiments were carried out in the laboratory to determine how the larvae recognize and capture prey. The diet consisted mainly of Cladocera, Chironomidae, and Hydrachnidia, living in peat mud together with the dragonfly larvae. Cannibalism also occurred. The prey is detected and recognised by tactile stimuli, visual and olfactory senses play virtually no role. The perfectly camouflaged larvae are typical sit-and-wait predators, hiding in mud and among plant debris. At the study sites, S. alpestris mostly occurred together with Aeshna juncea. The former predominated in small ponds and in runnels arising from seepages, while the latter dominated in large ponds. Aeshna juncea is considered the main predator of S. alpestris larvae, probably restricting local population sizes. The upper and lower altitudinal limits of distribution are briefly discussed with respect to global warming and the corresponding habitat changes.

Sympetrum frequens has recently been classified as an endangered species in 11 (26 %) Japanese prefectures, which are mainly located at lower elevations with higher temperatures. This study investigates the impact of warmer winters on the post-diapause development of overwintering eggs in S. frequens, a dragonfly species that depends on rice paddies for reproduction. We conducted two laboratory experiments comparing eggs from cooler northern regions (Fukushima Prefecture) and warmer southern regions (Miyazaki Prefecture). Eggs were exposed to temperature regimes simulating average winter conditions in these regions from 1990 to 2020. Our results revealed significant effects of regional temperature differences on hatching success and synchronization. Both, hatching rate and synchronized hatching coefficient, were significantly lower in eggs derived from Miyazaki province than in those from Fukushima. Eggs from warmer regions exhibited reduced hatching success and synchronization, indicating greater vulnerability to climate change. Elevated water temperatures (27.8°C) significantly reduced larval head width in eggs collected from the warmer southern region, supporting evidence that higher temperatures adversely affect larval development. These findings emphasize the critical role of global warming in reducing the reproductive success of S. frequens and highlight the need for targeted conservation strategies that address the species' climate-related vulnerabilities in rice paddy ecosystems.

The diversity of adult odonates in two artificial aquatic ecosystems in the Colombian Orinoquía region, a drainage canal and artificial ponds, was assessed in 2020 during both rainy and dry seasons. A total of 66 odonate species were recorded, 15 in the drainage canal and 51 in the artificial ponds. Overall, the assemblage was predominantly composed of common species; however, rare and threatened species (Acanthagrion fluviatile, Agriogomphus jessei) were also documented. Variation in rainfall between the two seasons influenced both species richness and community composition in each aquatic system. Although the ponds maintained higher overall richness, the drainage canal showed a significant increase during the rainy season compared to the dry season, reflecting a positive response to greater water availability and habitat heterogeneity and with a predominance of Zygoptera. In contrast, Anisoptera predominated in the ponds, which exhibited similar richness values between seasons, suggesting greater environmental stability. Despite their artificial origin and human-induced modifications, these water bodies serve as important habitats for various odonate species throughout the year, functioning as temporary refuges that buffer the ecological impacts of seasonal climatic fluctuations.

A biography of Dr. Thomas W. “Nick” Donnelly, geologist and influential leader of American odonatology is provided. A list of odonate taxa described by Nick and a list of odonate taxa named after him are appended.

A total of 587 adult Odonata belonging to six families, 25 genera, and 52 species were collected in 2005 from the tropical dry forests of Huatulco, Oaxaca, Mexico by bimonthly samplings of five days each for one year. Libellulidae with 26 species was the richest family, followed by Coenagrionidae (18), Calopterygidae (3), Aeshnidae and Gomphidae (2), and Lestidae (1). Argia with nine species was the most speciose genus, followed by Erythrodiplax (4), Dythemis, Erythemis, Hetaerina, Micrathyria, and Macrothemis (3). The remainder of the genera were represented by only two or one species. The observed species richness represented approximately 85.9 % of the estimated species richness for Huatulco. Maximum values of species richness, abundance, and diversity apparently coincide with the months of greatest rainfall. No relationship between phylogenetic diversity with temperature and precipitation was found.

Variation in female coloration of Anax imperator has been described and interpreted in several different ways. In particular it has been widely believed that at least some younger green females change colour to blue with increasing age. In this study, the coloration of mature females was analysed using our own photographs from north-western Germany as well as many sourced from the internet. Our results clearly contradict previous explanations of colour change. The existence of different colour forms can be better explained by a model of sex-limited polychromatism. We identified two colour forms of mature females: blue and green. We also tentatively differentiated between two differing forms among the blue females: a deep blue form matching the colour of the males, and a pale blue form, both of which begin oviposition early in the season. The pale form was seen most frequently in our study region and also in photographs on the internet from other regions in Europe, Africa, and Central Asia. By rearing a female of the pale blue form, we followed the development of the juvenile coloration and observed its variability depending on temperature. In pale blue females, S2 was still green at the time of mating when they were still immature, and became blue by the time oviposition had commenced. Although a colour change did occur, it only related to one abdominal segment. Due to their rarity in our study area, little is known about the deep blue androchrome females and those with a predominantly green abdomen. We have never seen gynochrome females with a pure green abdomen, which are known mainly from England, demonstrating that significant regional differences occur in the frequency of green phenotypes. Regional compositions of phenotypes presumably have also changed with time; there are indications that blue or partly blue females have also recently become common in the British Isles. The vast majority of photographs of mating showed females that were not yet fully coloured, with the exception of one old female. We suppose that the vast majority of all mating takes place in the immature stage.

The accurate identification of species is critical for any biological study. Sometimes the morphological similarity between species in the same genus makes this difficult, as with the male larvae and exuviae of Anax imperator and A. parthenope, two dragonflies that often occur syntopically. This paper examines the utility of 13 numerical criteria (based on nine measurements of the mentum, anal pyramid and femur in the metathoracic legs) and one morphological criterion (shape of the margin of the epiproct expansion: straight or notched) to separate exuviae of both species. The shape of the margin of the epiproct expansion provided correct identification of 89 % of exuviae and the ratio between length and width of the epiproct expansion was the most reliable of the criteria used.