Webspinners are small insects order Embiidina or Embioptera with tropical and subtropical distribution. They produce the fine silk in gland situation in the swollen foretarsi and live gregariously within silk galleries. They primarily graze on the outer bark of tree, decomposing leaf litter, mosses and lichens. The biodiversity, taxonomic position of webspinners in Thailand are poorly known. Therefore, the aims of this research were to study taxonomy, the species diversity as well as the distribution of webspinners from different habitat types in western Thailand. All specimens were identified based on morphological characters. A total of ten species and seven morphospecies from seven genera under four families of webspinners were recorded. The family Oligotomidae contained the greatest number of species (10) whereas the dominant genus found in this research was Ptilocerembia (4 species) of Notoligotomidae. There are two morphospecies of Embiidae: Oedembia sp.1 and Oedembia sp. 2, four morphospecies of Notoligotomidae: Ptilocerembia sp.1, Ptilocerembia sp.2, Ptilocerembia sp.3 and Ptilocerembia sp.4, ten species of Oligotomidae: Aposthonia borneensis, A. ceylonica, A. problita, Eosembia auripecta, E. lamunae, E. paradorni, Lobosembia mandibulata, Oligotoma humbertiana, O. nigra and O. saundersii, and one morphospecies of Teratembiidae (Oligembia sp.1). Three species of Oligotoma were recorded for the first time and three new species; Aposthonia problita, Eosembia lamunae and E. paradorni were discovered. In addition, the dichotomous and pictorial keys to families, genera and species levels and description of the webspinners from this study are presented, especially the keys to Thai webspinners based on adult females are provided for rapid observation in the field study or in the laboratory examination. Of all studied habitat characteristic types, the highest number of species (6) occurred in dry evergreen forests, mixed deciduous forests and forest parks, whereas the lowest numbers of species (1) occurred in beach forests and coniferous plantations. Three species of the Oligotoma were found only in human exploited areas, particularly in forest parks throughout the study areas, which suggested they might have been introduced to the areas. On the other hand, Eosembia lamunae, Lobosembia mandibulata, Oedembia sp.2, Oligembia sp.1 and Ptilocerembia sp.2 were found solely in natural forests. It might be expected that these species may inhabit restricted habitats having specific requirements within these forests. Moreover, the most common species, which was distributed throughout the western Thailand, was Eosembia auripecta and was able to be encountered in both human exploited areas and natural forests.
