This study explores the external morphology of larva of Cricula trifenestrata Helfer at the fifth instar stage, focusing on sexual dimorphism, scoli, and fluorescence hair warts. The larva displays a black body adorned with varying shades of orange to crimson–red transverse stripes and small yellow dorsal spots. Longitudinal stripes with fluorescent warts are observed in the subspiracular region, accompanied by an overall coverage of long white hairs. These distinctive features, including scoli and fluorescence hair warts, serve as effective defense mechanisms against predators and parasitoids. The results enhance our understanding of C. trifenestrata Helfer larval biology, providing valuable insights for entomology and evolutionary biology. The identification of species-specific adaptations, particularly the presence of scoli and fluorescence hair warts, underscores their significance in shaping survival strategies and ecological interactions.

A survey of the ostracod fauna in the Chi River Basin in three provinces (Maha Sarakham, Kalasin and Roi Et) of northeast Thailand uncovered three new species of the tribe Cyprettadopsini of the Cypridopsinae: Cyprettadopsis hanjavanitae sp. nov., C. kalasinensis sp. nov. and Pseudocypretta sangpradubae sp. nov. Apart from its different soft part morphology, P. sangpradubae sp. nov. can be obviously distinguished from other Pseudocypretta by the valve ornamentation with strong pits and densely arranged long setae. The two new Cyprettadopsis species can be primarily discriminated from the type species, Cyprettadopsis sutura Savatenalinton, 2020, by their subtriangular and subovate carapace shape in, respectively, lateral and dorsal views. Cyprettadopsis hanjavanitae sp. nov. mainly differs from C. kalasinensis sp. nov. by soft parts aspects, especially the caudal ramus. The discovery of these three new species, together with a literature review, provides additional diagnostic features of the Cyprettadopsini. Most of them include the dorsal subapical seta on the basal segment of the maxilla palp, the g seta on the third thoracopod, the pseudosegmentation on the natatory setae of the second antenna, and the color pattern on the valve surface. In addition, setae with thick bases, which are found on the valve surfaces of all species of Cyprettadopsini, have so far been recognized only in the Cypridopsinae. Although the occurrence of marginal septa is an interspecific variable feature in Pseudocypretta and Cyprettadopsis, the modes of appearance are specific to their genera. Herein, the distinguishing features and a key to the genera of the Cyprettadopsini are updated, and Mixtadopsis franki (Ferreira et al., 2023) nov. comb. is introduced. Pseudocypretta sangpradubae sp. nov. is the second Pseudocypretta described from Southeast Asia, and the first one from Thailand. Currently, the number of Cypridopsinae species in Thailand is 15, belonging to six (of a total of seven) tribes, indicating the high diversity at the tribe level of this subfamily in Thailand.

Cricula trifenestrata Helfer was recently documented on cinnamon (Cinnamomum spp.), a novel host plant in Thailand. We compared life history and behavior under natural field, semi-natural caged, and laboratory conditions on cinnamon, plus opportunistic collection from hog plum (Spondias pinnata). Laboratory rearing significantly extended development (62.30 ± 3.68 days) versus field conditions (56.30 ± 1.83 days, p < 0.001) through delayed egg and pupal stages, indicating life history plasticity. We discovered density-dependent oviposition plasticity (linear arrangements in field: 155.6 ± 84.9 eggs/batch; clustered in laboratory) and novel gregarious cocooning behavior, where 85.1% of individuals (n = 47 sites) aggregated to form communal clusters with unique reticulated architecture. Female cocoon shell ratio (CSR) was significantly higher in laboratory (5.02 ± 0.72%) and hog plum cohorts (5.30 ± 0.30%) than field conditions (3.92 ± 0.51%, p = 0.002). Opportunistic rearing yielded >2 kg fresh cocoons, with clusters reaching 0.220 kg. These findings establish biological baselines for C. trifenestrata Helfer on cinnamon, reveal sophisticated social behaviors expanding lepidopteran sociality concepts, and demonstrate commercial potential for sustainable sericulture integrated with pest management.