Meloinae

Meloinae can be distinguished from other Meloidae subfamilies by combinations of adult and larval morphological features. Adults typically have fully developed elytra (unlike the flightless, abbreviated elytra of some Meloinae such as Meloe). Larval stages include the distinctive triungulin (first instar), a mobile, heavily sclerotized form adapted for host-seeking, followed by grub-like and coarctate (sedentary, non-feeding) phases. Tribal-level identification relies on antennal structure, tarsal formula, and male genitalia; genus-level characters include body form, coloration patterns, and degree of sexual dimorphism.

Habitats vary widely by tribe and genus. Epicauta species occupy temperate and semi-arid regions of the Nearctic and Neotropics, including grasslands, roadsides, and agricultural areas. Meloe species occur in diverse terrestrial habitats from lowland to montane regions, including orchards and grasslands. Psalydolytta species have been documented in pearl millet agricultural fields in West Africa. Some genera show affinity for specific substrates: Cysteodemus (desert spider beetles) in arid environments, and Tegrodera (iron cross blister beetles) in desert regions.

Cosmopolitan distribution with major centers of diversity in the Nearctic, Neotropical, Palearctic, Afrotropical, and Oriental regions. The genus Epicauta shows greatest diversity in temperate and semi-arid regions of the Americas, with tropical Middle America acting as a biogeographic barrier. Meloe is primarily Holarctic with richer development in the Old World, including Mediterranean endemics. Psalydolytta occurs in West Africa. The tribe Mylabrini is predominantly Afrotropical and Palearctic.

Adults are generally phytophagous, feeding on leaves, flowers, and pollen of diverse plants. Specific host associations vary by genus: Epicauta species are documented on multiple crop plants; Meloe semicoriaceus has been reared on Taraxacum officinale. Laral diet is heterogenous: first instar triungulins of some genera are parasitoids or predators of grasshopper egg pods (Psalydolytta) or hypermetamorphic parasites of bees (some Nemognathinae relatives; bee-associations in Meloinae require confirmation by genus).

Hypermetamorphic development with four distinct larval phases: (1) triungulin (mobile, heavily sclerotized first instar adapted for host location), (2) first grub (feeding stage, often on host eggs or provisions), (3) coarctate (non-feeding, quiescent transitional stage), and (4) second grub (final feeding stage before pupation). This developmental pattern has been confirmed in Psalydolytta species and is characteristic of the subfamily.

Courtship behavior has been documented in multiple genera and involves stereotyped sequences. In Meloe semicoriaceus, males pursue females, engage in antennal touching and palpal contact, mount the female's back facing the same direction, and slide backward for genital contact; copulation lasts 5–25 minutes. In Epicauta atomaria, males exhibit quiescent periods, antennal rubbing, and mounting. Males of some species show persistent courtship despite female avoidance behaviors. Sexual dimorphism in antennae (modified segments in males) and tibial spurs is common.

Adults function as herbivores in terrestrial ecosystems, with some species reaching pest status in agriculture. Larval stages of some genera act as natural enemies of grasshoppers (Psalydolytta) or potentially bees, contributing to population regulation of these groups. The subfamily represents a significant component of blister beetle diversity in most terrestrial biomes.

Several genera contain economically important agricultural pests. Epicauta species damage diverse crops including legumes, solanaceous plants, and ornamentals; adults are highly mobile and can aggregate to cause significant defoliation. Psalydolytta pilipes causes yield losses in pearl millet in West Africa, with whole inflorescences destroyed at densities of approximately 12 beetles per head. Meloe species (oil beetles) contain cantharidin and have been used historically in traditional medicine, though this use is hazardous. Cantharidin from meloine beetles causes blistering and is toxic to humans and livestock.

• NemognathinaeAlso a subfamily of Meloidae with hypermetamorphic development and triungulin larvae; distinguished by adult morphological characters including antennal structure and larval host associations (Nemognathinae are predominantly bee parasites, while Meloinae show more diverse larval habits including grasshopper egg predators and phytophagy)
• TetraonycinaeSmaller Meloidae subfamily with distinct adult and larval morphology; Tetraonycinae typically have more elongated body forms and different antennal structure

• hypermetamorphosis
• triungulin
• phytophagous
• cantharidin
• agricultural pest
• sexual dimorphism
• courtship behavior

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Meloidae Holdings | Entomology Research Museum
• Modeling Current and Future Distribution of Epicauta Dejean (Meloinae, Epicautini) under Changing Climate Conditions in America
• Phylogenetic analysis and redefinition of the maculata species group of Epicauta (Meloidae: Meloinae: Epicautini)
• Redescription of the Blister Beetle Meloe semicoriaceus Fairmaire, 1891 (Coleoptera: Meloidae: Meloinae) with Notes on Courtship Behavior
• Field studies on the biology and economic importance of Psalydolytta spp. (Coleoptera: Meloidae: Meloinae) in Mali, West Africa
• Endemic and cryptic: different biogeographic histories of three Italian blister beetles of the genus Meloe (Coleoptera: Meloidae: Meloinae: Meloini)
• Bionomics of Nearctic Bee-Associated Meloidae (Coleoptera). A Comparative Analysis of Larval Host-Seeking Behavior among the Meloinae and Nemognathinae1,2,3
• Sexual behaviour of the blister beetle Epicauta atomaria (Germar), with remarks on the bionomics of Epicauta maculata species group (Meloidae: Meloinae: Epicautini)