The enigmatic Australo-Pacific genus Geochus Broun includes 26 described species from New Zealand and one from Lord Howe Island. They are abundant in leaf litter, and most species are easily recognized as adults by their odd squat form, lack of tarsal claws and flattened larvae that mine dead leaves. In older classifications, Geochus was placed in Curculioninae or Molytinae, but has been regarded more recently as an aberrant molytine or member of Phrynixini. A phylogeny of weevils that included Geochus from New Zealand and Lord Howe Island, representatives of 32% of the weevil genera in New Zealand, selected Rhamphini and Viticiini, and the South African genus Afrogeochus Rheinheimer, placed Geochus as the sister taxon of Viticis Lea, well outside Molytinae or Curculioninae at the base of a grade consisting of Entiminae, Cyclominae, and Phrynixini. Afrogeochus is transferred from Curculioninae to Cossoninae, based on molecular evidence. The absence of tarsal claws has hitherto been a distinct character of Geochus. However, their retention is reported in Geochus kuscheli Leschen, Davis, Brown, Brav-Cubitt, and Buckley, new species, a species that is sister to the remaining members of the genus. The status of type specimens for all 26 previously described Geochus species is reviewed, and eleven lectotype designations are made to promote a stable taxonomy for: Geochus apicalis Broun, Geochus convexus Broun, Geochus inaequalis (Broun), Geochus lateralis Broun, Geochus marginatus Broun, Geochus pictulus Broun, Geochus plagiatus Broun, Geochus politus (Broun), Geochus puncticollis Broun, Geochus rugulosus Broun, Geochus setiger Broun, Geochus similis Broun, Geochus squamosus Broun, Geochus suffusus Broun, Geochus tibialis Broun, and Geochus variegatus Broun. The 27 known Geochus species are grouped into 13 species groups, and a key to the adults of these species groups is provided.

The female of Bruchus nikdeli Delobel and Sadeghi, unknown until now, is described for the first time. Distinguishing characters of the female and detailed structures of the genitalia of both sexes are presented with digital photographs. The species is also recorded as a new country record from Turkey based on specimens reared from seeds of Vicia canescens L. (Fabaceae), confirming this as a host plant for B. nikdeli in Turkey.

Nine species of Meloidae are recorded from the Baja California Peninsula, Mexico for the first time. One of these, Lytta cochimi Pinto, new species, is described herein. In addition to these new records, collections which significantly expand the peninsular distribution of species previously recorded from the peninsula are documented. A list of all meloid species now known to occur in Baja California is included.

The Palearctic species Trechus obtusus Erichson is reported for the first time from eastern North America. Recent collections in Virginia and North Carolina (new state records) indicate the establishment of the species in the Appalachian region. DNA was extracted from six individuals, and the COI barcoding region was sequenced. All but one of the COI barcode haplotypes were identical to those of T. obtusus collected in western North America. No matches were found with available Palearctic sequences. Individuals of T. obtusus were collected from caves and forest leaf litter, both habitats used by native trechine species. Sampled Appalachian populations of T. obtusus appear to be small, with the exception of the population in Mebane Saltpeter Cave (Pulaski County, VA), which is large and included teneral individuals. Currently, there is no evidence that the species is displacing or otherwise negatively affecting native trechines. The species should be monitored carefully going forward, and targeted sampling of synanthropic habitats will be the best method for early detection.

In insects, mating performance and female post-mating reproductive fitness is closely related to female and male density. In nature, females and males of the willow leaf beetle, Plagiodera versicolora (Laicharting), exhibit the phenomenon of swarming damage. This study investigated the effects of female and male density on their mating performance and on female post-mating fecundity, egg hatching rates, and egg-laying patterns. Female and male density had a significant positive effect on the time from pairing to successful mating and on female fecundity, the duration of the egg-laying period, and the number of egg clutches, but it had a significant negative effect on the egg hatching rate. Female and male density had no significant effect on female post-mating longevity and the number of eggs per clutch. Our study shows that variation in female fecundity and egg-laying patterns is an adaptive strategy for P. versicolora at relatively high population densities. This strategy helps to expand the distribution of offspring and lower the competition for food resources among offspring, which, in turn, helps to maintain or increase population abundance.

Sphaeridium sundense Suzumura, van Berge Henegouwen, and Budi, new species is described and illustrated from Sumatra, Java, and the Lesser Sunda Islands, Indonesia. A description of the new species, habitus photographs, and illustrations of diagnostic characters are provided with differential characters to separate it from the widespread and co-existing Sphaeridium quinquemaculatum Fabricius, 1798.

This is the first scientific report of the behavior of adult Gerstaeckeria bifasciata (Gerstaecker, 1860) and the damage they cause on the globose cactus Stenocactus obvallatus (DC.) A. Berger ex A.W. Hill (Cactaceae). During 2017, we surveyed a population of S. obvallatus (N = 337 plants) in Tierra Blanca, Guanajuato, Mexico, recording the damage that they presented in their stems. A year later, a second survey was carried out, recording survival or death of the plants. Although 86% of plants showed ribs damaged by this weevil in the first census, only a small percentage of them died (5.64%). Our study suggests that S. obvallatus has evolved mechanisms that allow it to tolerate herbivory by this weevil, as we recorded G. bifasciata adults feeding from both caulinary (ribs) and reproductive structures (floral buds and flowers) of S. obvallatus.

The Miridiba lamellata species group (Coleoptera: Scarabaeidae: Melolonthinae: Rhizotrogini) is established. Miridiba dugonga Gao, new species is described and illustrated. A key to the species groups in the genus Miridiba Reitter is also provided. Miridiba lamellata Gao and Fang, 2019 is recorded from Vietnam for the first time.

Hydrovatus onigiri Watanabe and Biström, new species is described from Japan. The new species is similar to Hydrovatus subtilis Sharp, 1882, but it is distinguishable from the latter by male antennomeres 4–6 being the broadest (rather than antennomeres 6–8), poorly developed male stridulatory apparatus, and an almost evenly curved penis apex. Hydrovatus onigiri, new species is the 20th species of the H. confertus species group, and 10th Hydrovatus Motschulsky species known from Japan.