<p>Field experiments were conducted during the early and late planting seasons of 2022 at the Federal University of Agriculture, Abeokuta, Nigeria, to quantify watermelon yield loss in relation to insect pest infestation using correlation and linear regression models. The study evaluated the relationship between pest density and key crop performance indicators, including leaf damage, plant survival, and marketable fruit yield. Results showed that leaf-feeding beetle density was strongly and positively associated with the proportion of damaged leaves and severity of leaf injury, while exhibiting a significant negative relationship with plant survival rate in both planting seasons. Marketable fruit yield declined significantly with increasing pest density, with leaf-feeding beetles identified as the most influential pest species. Although individual pests contributed significantly to yield reduction, their combined effects on yield were not strictly additive. The regression models explained a substantial proportion of the variation in crop performance, indicating that insect pest infestation is a major determinant of watermelon productivity. No seasonal differences in the damage parameters observed which could indicate consistent pest impact across seasons. These findings highlight the importance of pest monitoring and provide a quantitative basis for predicting yield loss in watermelon production systems. The developed models can support decision-making in integrated pest management strategies aimed at minimizing yield losses.</p>