Hirudinaria manillensis is an ephemeral, blood-sucking ectoparasite, possessing anticoagulant capacities with potential medical applications. Analysis of codon usage patterns would contribute to our understanding of the evolutionary mechanisms and genetic architecture of H. manillensis, which in turn would provide insight into the characteristics of other leeches. We analysed codon usage and related indices using 18,000 coding sequences (CDSs) retrieved from H. manillensis RNA-Seq data. We identified four highly preferred codons in H. manillensis that have G/C-endings. Points generated in an effective number of codons (ENC) plot distributed below the standard curve and the slope of a neutrality plot was less than 1. Highly expressed CDSs had lower ENC content and higher GC content than weakly expressed CDSs. Principal component analysis conducted on relative synonymous codon usage (RSCU) values divided CDSs according to GC content and divided codons according to ending bases. Moreover, by determining codon usage, we found that the majority of blood-diet related genes have undergone less adaptive evolution in H. manillensis, except for those with homologous sequences in the host species. Codon usage in H. manillensis had an overall preference toward C-endings and indicated that codon usage patterns are mediated by differential expression, GC content, and biological function. Although mutation pressure effects were also notable, the majority of genetic evolution in H. manillensis was driven by natural selection.

The article revised most species of genera of Modicogryllus Chopard, 1961, Gryllodinus Bolívar, 1927, Eumodicogryllus Gorochov, 1986, Svercacheta Gorochov, 1993 and Turanogryllus Tarbinsky, 1940 and proposed a new species, Gryllodinus jijilacus sp. nov., four synonyms, Mirigryllus He, 2020 syn. nov., Gryllus bordigalensis (=Eumodicogryllus bordigalensis) Latreille, 1804 syn. nov., Gryllus chivensis (=Eumodicogryllus chivensis) Tarbinsky, 1930 syn. nov. and Gryllopsis aelleni (=Turanogryllus aelleni) Chopard, 1954 syn. nov., seven new combinations, Modicogryllus (Modicogryllus) nigrus (He, 2020) comb. nov., Mitius vaturu (Otte & Cowper, 2007) comb. nov., Loxoblemmus abrictos (Otte, 2007) comb. nov., Modicogryllus (Promodicogryllus) nigericus (Chopard, 1961) comb. nov., Eumodicogryllus chinensis (Weber, 1801) comb. nov., Eumodicogryllus vicinus (Chopard, 1968) comb. nov. and Svercacheta semiobscurus (Chopard, 1961) comb. nov., and re-established a species, Modicogryllus (Modicogryllus) latefasciatus (Chopard, 1933), as well as redescribed species of Modicogryllus (Promodicogryllus) consobrinus (Saussure, 1877), Svercacheta siamensis (Chopard, 1961) and Turanogryllus lateralis (Fieber, 1853).

Eight species comprise the genus Svistella Gorochov, 1987 worldwide. Most are yellow or yellowish brown, and, two of them are colorful. With the exception of the colorful species, Svistella bifasciata (Shiraki, 1913) and Svistella chekjawa Tan & Robillard, 2012, another was discovered in China. Svistella argentata sp. n. is very similar to S. bifasciata, but different in coloration and features of the male genitalia. Svistella tympanalis He et al., 2009 is found to be a junior synonym of Svistella rufonotata (Chopard, 1932).

Here we report two new species of the swordtail crickets (Orthoptera: Trigonidiidae; Trigonidiinae) from Yunnan and Guangxi Province, China. One species (Trigonidium rubrumoculus sp. nov.) belongs to the genus Trigonidium, and we describe a new genus for the other species (Polycomus gen. nov., Polycomus exspiravit sp. nov.). The new genus resembles Amusurgus Brunner von Wattenwyl, 1893 in appearance but differs in the structure of the male genitalia. Descriptions, illustrations, and distributions of these new species are provided.

The abundance of insects in Burmese amber illustrates a highly diverse insect community of the mid-Cretaceous, but the records of crickets are relatively rare. Here, we erect two new genera with two new species, Birmanioecanthus haplostichus gen. et sp. nov. and Apiculatus cretaceus gen. et sp. nov., based on two new specimens from northern Myanmar amber. These new species can be assigned to the subfamily Oecanthinae (Orthoptera: Gryllidae) by their prognathous head, slender body and metatibiae, and protibiae with large tympana. These new findings are the first and earliest fossil record of tree crickets and shed light on the evolution of Oecanithinae.