Neotropical species of the Elachista praelineata species group are reviewed. Five species are recognized in the Neotropics. A new species, Elachista stonisi sp. nov., and female of E. albisquamella Zeller, 1877 are described and illustrated with photographs of the adults, some of the immature stages, female genitalia, and leaf mines. The female of E. lata Sruoga, 2010 is associated with the male based on morphology and the comparison of partial mitochondrial COI sequences. Identification keys to the Neotropical species of E. praelineata species group, based on male and female genitalia, are provided.

The diversity of non-biting midges (Chironomidae, Diptera) remains an unresolved topic, with estimates of species numbers ranging from 6000 to 15,000 according to various authors. To assess Chironomidae diversity in Lithuania, we evaluate the effectiveness of COI gene-based species delimitation methods for providing rapid diversity estimates. Nevertheless, differences between tree-based and distance-based approaches can result in varying group classifications, which may cause species numbers to be overestimated or underestimated. For our study, we analyzed a dataset of 109 specimens sampled from six Lithuanian streams. By applying multiple methods, such as Assemble Species by Automatic Partitioning (ASAP), Automatic Barcode Gap Discovery (ABGD), the generalized mixed Yule-coalescent (GMYC) model, and the Bayesian implementation of the Poisson Tree Processes (bPTP) model, we found that species estimates ranged from 28 to 58. Among these methods, ASAP proved to be the most effective for our dataset, identifying 58 putative species. These results reinforce our assumption that the current understanding of Chironomidae species diversity is incomplete.

Based on research carried out from 2016 to 2018 there are twenty-six species of aphids of the tribe Eulachnini in Lithuania. Seventeen are members of the subgenus Cinara of the genus Cinara, three of the subgenus Cupressobium and two of the subgenus Schizolachnus. In addition, there are four species of the genus Eulachnus. Summarized information on the distribution and host specificity of Eulachnini in Lithuania is presented. Nine species were in all climatic regions of Lithuania: C. (Cinara) brauni, C. (Cinara) hyperophila, C. (Cinara) neubergi, C. (Cinara) piceicola, C. (Cinara) pinea, C. (Cinara) pini, C. (Cinara) pruinosa, C. (Cupressobium) cupressi and C. (Cupressobium) juniperi. Five species of Lithuanian Eulachnini inhabit host plants of the genus Picea, three live on Larix, thirteen on Pinus, one on Abies, one on Thuja and three on Juniperus. Cinara (Cinara) piniphila was recorded on Pinus mugo and C. (Cinara) nuda on Pinus heldreichii for the first time. Partial COI and EF-1α sequences of C. (Cinara) hyperophila, C. (Cinara) pilosa and C. (Cinara) piceicola were obtained for the first time. Partial sequences of mitochondrial (COI) and nuclear (EF-1α) DNA of Lithuanian samples were used to explore molecular diversity using NJ trees, Automatic Barcode Gap Discovery (ABGD), General Mixed Yule Coalescent (GMYC) and Poisson Tree Processes (PTP). Species delimitation using GMYC (both on COI and EF-1α sequences), PTP (BI on COI) and ABGD (EF-1α) were the most consistent with traditional classifications. Pairwise between-species sample divergences (COI and EF-1α fragments) of the samples of the species complex C. (Cinara) pinea - C. (Cinara) piniphila indicate it is composed of a single species. Of the species of aphids that live on conifers, there are seven species of the tribe Eulachnini that are likely to shortly colonize Lithuania.

Nearctic aphid Cinara splendens (Gillette and Palmer, 1924) was collected on ornamental Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in South Bohemia in 2009. It was the first record of this species in the Palaearctic region. The aim of this research was to study the bionomy of this species in Central Europe and to make descriptions of all available morphs, as previous morphological descriptions of C. splendens appeared to be incomplete. Six monitoring sites of this species were established in South Bohemia and were then regularly attended in the period of 2009–2019. The colonies of C. splendens were observed; its natural enemies and honeydew users were also registered. Aphids were collected for the microscope slide preparation, followed by the evaluation of thirty of the basic quantitative and seven qualitative morphological characteristics. Partial sequences of mitochondrial COI and nuclear EF-1α were used to confirm morphology-based identification and to compare samples from the Czech Republic with those of North American origin. Cinarasplendens survived successfully under new ecological conditions, but its population density remained quite low, except for 2009 and 2019, due to a synergistic effect of the dry weather and very high population density of the adelgid Gilletteella coweni (Gillette, 1907), which is a key pest of Douglas fir in the Czech Republic. The principle predators were coccinellid beetles, while the aphidophagous hover flies were less abundant. Together with a weak ability to migrate due to a low number of alate viviparous females in population, C. splendens cannot be a potential pest of P. menziesii in Central Europe.

The genus Hexatoma Latreille, 1809 is a large group of aquatic crane flies, with almost 600 species worldwide. The largest subgenus is Eriocera Macquart, 1838, which includes all nine species known from the Korean Peninsula. Molecular methods were used to associate Hexatoma larvae with their putative adult species from South Korea. Mitochondrial Cytochrome c Oxidase Subunit I (COI) gene fragment sequences (DNA barcodes) of recently collected adults of H. (E.) gifuensis, H. (E.) ilwola, H. (E.) pernigrina, and H. (E.) pianigra were compared with twelve sequences of Hexatoma larvae. The larvae of H. (E.) pernigrina, H. (E.) pianigra, and H. (E.) gifuensis were associated with their putative adults. The larvae of H. (E.) gifuensis and H. (E.) pianigra and the larvae and pupae of H. (E.) pernigrina are described and illustrated. The larvae of two species not associated with any adult are described, and their COI gene fragment sequences (DNA barcodes) are presented. This paper presents the morphological characteristics suitable for distinguishing larval species. A key for the identification of larvae of the genus Hexatoma on the Korean Peninsula has been compiled. H (E.) sachalinensis is recorded from the Korean Peninsula for the first time. Our study is the first contribution to the Hexatoma larvae taxonomy using phylogenetic analysis based on mitochondrial COI fragment (DNA barcode) and one of the first attempts to reveal phylogenetic relationships between Hexatoma species using molecular markers.