Abstract: The study examines interspecific interactions between Bemisia tabaci (Hem., Aleyrodidae) and Liriomyza sativae (Dipt., Agromyzidae) feeding on pumpkins and cucumbers. L. sativae density on control pumpkins and cucumbers peaked 3 and 2 weeks after adults were seen, respectively. Compared with controls, L. sativae densities observed for weeks 3–6 and 2–6 in the B. tabaci‐pre‐infested plants were significantly lower, respectively (F2.00 = 22.66, P < 0.01). The survival of L. sativae larvae transplanted to B. tabaci‐pre‐infested pumpkins and cucumbers was 16.06%, 10.02% and 13.09%, 9.21%, whereas those transplanted to control plants were 52.20%, 36.06% and 48.25%, 28.22% after 5 and 10 days, respectively (χ2 = 6.9, d.f. = 1, P < 0.01). Pupation rates of L. sativae feeding on control plants were 20.25% and 16.45%, whereas those feeding on the B. tabaci‐pre‐infested plants only 4.08% and 4.21%, respectively (χ2 = 7.0, d.f. = 1, P < 0.01). The length and number of mines of L. sativae on the control pumpkins and cucumbers were 54.05%, 54.10% and 89.06%, 76.22% longer or higher than those on B. tabaci‐pre‐infested plants, respectively. Leaf positions of L. sativae feeding on the plants were also affected by B. tabaci‐pre‐infested. These results showed that B. tabaci infestations had a significantly negative effect on L. sativae when they were feeding simultaneously on the same host plant.