Parasites are important players in ecological communities that can shape community structure and influence ecosystem energy flow. Yet beyond their effects on hosts, parasites can also function as an important prey resource for predators. Predators that consume infectious stages in the environment can benefit from a nutrient-rich prey item while concurrently reducing transmission to downstream hosts, highlighting the broad importance of this interaction. Less clear, however, are the specific characteristics of parasites and predators that increase the likelihood of consumption. Here, we determine what combination(s) of predator and parasite morphological traits lead to high parasite consumption. We exposed the infectious stages (cercariae) of five trematode (fluke) taxa to aquatic insect predators with varying foraging strategies and morphologies. Across the 19 predator—parasite combinations tested, damselfly predators in the family Coenagrionidae were, on average, the most effective predators of cercariae, consuming between 13 and 55% of administered cercariae. Large-bodied cercariae of Ribeiroia ondatrae had the highest average vulnerability to predation, with 37–48% of cercariae consumed. The interaction between predator head width and cercariae tail size strongly influenced the probability of consumption: small-bodied predators were the most effective consumers, particularly for larger tailed parasites. Thus, the likelihood of parasite consumption depended strongly on the relative size between predator and parasite. Our study helps establish that predation on free-living parasites largely follows a broader predator–prey framework. This will help to identify which predator and parasite combinations will likely have high consumptive interactions, potentially reducing parasite transmission in natural populations.

寄生虫是生态群落中的重要参与者，可以塑造群落结构并影响生态系统能量流动。然而，除了对宿主的影响之外，寄生虫还可以作为捕食者的重要猎物资源。在环境中消耗传染性阶段的捕食者可以从营养丰富的猎物中受益，同时减少向下游宿主的传播，突出了这种相互作用的广泛重要性。然而，不太清楚的是寄生虫和捕食者的具体特征会增加消费的可能性。在这里，我们确定捕食者和寄生虫形态特征的哪些组合会导致高寄生虫消耗。我们将五种吸虫（吸虫）分类群的感染阶段（尾蚴）暴露于具有不同觅食策略和形态的水生昆虫捕食者。在测试的 19 种捕食者 - 寄生虫组合中，豆娘科的豆娘捕食者平均是尾蚴最有效的捕食者，消耗了 13% 到 55% 的尾蚴。大型尾蚴Ribeiroia ondatrae对捕食的平均脆弱性最高，消耗了 37-48% 的尾蚴。捕食者头部宽度和尾蚴尾巴大小之间的相互作用强烈影响了消费的可能性：体型较小的捕食者是最有效的消费者，特别是对于较大的尾寄生虫。因此，寄生虫消费的可能性在很大程度上取决于捕食者和寄生虫之间的相对大小。我们的研究有助于确定对自由生活寄生虫的捕食在很大程度上遵循更广泛的捕食者-猎物框架。这将有助于确定哪些捕食者和寄生虫组合可能具有高消耗性相互作用，从而有可能减少自然种群中的寄生虫传播。