<p>Acari, including mites and ticks, pose significant challenges in agriculture, horticulture, and medicine. Among these, agricultural concerns are particularly critical, as many mite species directly affect crop health and productivity. The genome sizes of Acari vary widely, reflecting their diverse ecological roles and life history traits. This variation often corresponds to differences in reproductive strategies, parasitic behaviors, and adaptation to specific environments. Here, to better understand evolution trends in Acari, we (1) estimated the genome size of six mite species using flow cytometry, (2) compiled publicly available genome data for additional Acari species, and (3) analyzed the relationships between genome features (size, repetitive elements, GC content, gene numbers) and ecological or life history traits. Our findings reveal that predatory and parasitic Acari, particularly blood-feeding species, tend to have larger genomes compared to herbivorous and microbivorous species, suggesting that diet and ecological roles may drive genome expansion. Additionally, genome size correlates positively with repetitive elements, which significantly contribute to genome variability. Furthermore, larger genomes are linked to higher GC content and gene numbers, reflecting increased functional complexity and genome stability. These findings align with hypotheses on genome size determinants, highlighting the influence of ecological and evolutionary pressures on Acari genome architecture. Understanding their genome structure is crucial for uncovering the genetic basis of their ecological and physiological diversity, which underpins their adaptability and resilience. Such insights are vital for developing targeted pest management strategies to mitigate their agricultural impact and promote long-term sustainable practices.</p>