ABSTRACT Frog‐bitting midges (Corethrellidae) are widespread micropredators that feed on frog blood. Furthermore, frog‐biting midges may carry pathogens, an important cause of worldwide amphibian declines. Female midges usually target calling male frogs by using acoustic cues. However, how midges target frogs that use conspicuous visual cues, especially diurnal species, is still poorly understood. We explored micropredation by corethrellid midges on two syntopic diurnal frogs, Hylodes asper and H. phyllodes , in Brazil's Atlantic Forest. We tested host selection (species and sex) as well as the spatial and temporal patterns of micropredation. Midges were recorded exclusively on H. asper , indicating host preference, potentially linked to acoustic parameters preferred by midges. Males were more frequently targeted, particularly those calling near the main current of the streams. Yet, midge abundance per individual did not differ between sexes, with unusual high abundance on females. Midges concentrated on the nostrils and gular region, likely due to higher vascularization. Midge activity was strictly diurnal, despite frogs being available at night while resting exposed on vegetation. Micropredation is likely influenced by precipitation, especially under high maximum temperatures. These patterns suggest that both host traits and environmental conditions shape micropredation dynamics for frogs that use visual cues. Considering that midge hematophagy can impose direct physiological costs, as well as carry pathogens, micropredation could significantly impact fitness at the population level. This may be particularly critical for H. asper , which has rapid annual turnover and documented susceptibility to pathogens, which highlights the importance of integrating behavior and environmental factors into midge‐frog interactions.
Serrano et al. (2026) studied this question.