Evidence indicates that environmental pollution, particularly agrochemicals, contributes to the decline of wild insect populations and the losses managed honey bee colonies. In Switzerland and the EU, Plant Protection product (PPP) authorization follows a tiered risk assessment scheme using theoretical models based mainly on honey bee data. This framework was designed for treated agricultural landscapes (i.e., in-crop), and may thus have uncertainties regarding PPP deposition in non-treated areas – such as biodiversity zones and flower strips. Here, we show that Spinosad drift on wild flowers significantly reduced survival and reproductive success of foraging Osmia bicornis. Under semi-field conditions, we evaluated the spray drift of two commonly used insecticides, Spinosad and Acetamiprid, by assessing their vertical distribution and deposition at field edges following application. Additionally, we examined potential lethal (i.e., mortality) and sublethal (i.e., reproductive output and emergence success) effects on female O. bicornis foraging on drift-treated plants maintained under tunnel conditions. Residues in nectar, pollen, food provisions, and plant material were quantitatively analyzed using UHPLC MS/MS. The data revealed that one day post-application pollen provisions had mean concentrations of 329 µg/kg (Acetamiprid) and 1445 µg/kg (Spinosad). These levels declined to 109 µg/kg and 509 µg/kg after three days and further to 22 µg/kg and 84 µg/kg after seven days, respectively. Spinosad treated groups resulted in a significant reduction in female survival (P < 0.001), with a 52.7% decrease in survival after seven days. Furthermore, a significant reduction in reproductive output (P < 0.001) and emergence success (73.8%; P < 0.001) was observed. In contrast, Acetamiprid-treated groups showed no significant differences compared to controls (P > 0.20), yet they did significantly differ from the Spinosad treatment (P < 0.001). Our results indicate that pesticide drift can significantly harm O. bicornis, suggesting that while current regulations and mitigation measures may protect honeybees, they may not sufficiently safeguard solitary bees. Risk assessments must consider their unique vulnerabilities for better pollinator conservation. Existing measures focus on honey bees, but their effectiveness for wild bees remains uncertain due to behavioral differences affecting pesticide exposure.