Hydrazone derivatives possess good antifungal and insecticidal activities and their structures are used in pesticide design. In the present study, for the first time, ten hydrazone derivatives (1–10) were evaluated for their antifungal activity against Colletotrichum, Botrytis, Fusarium, and Phomopsis species and for their biting deterrent and larvicidal activity against Aedes aegypti, the yellow mosquito. The 96-well microbioassay revealed that compounds 3, 5, 7, and 9 showed strong antifungal activity at 30 lM against Phomopsis obscurans, whereas only two compounds (5 and 9) demonstrated strong antifungal activity against Phomopsis viticola. Compound 5 showed the highest biting deterrent activity against Ae. aegypti when compared with N,N-diethyl-meta-toluamide, the positive control at 25 nmol/cm2. Compound 9 exhibited the highest larvicidal activity in toxicity bioassay with LD50 values of 57.4 and 4.35 ppm and LD90 values of 297.8 and 19.1 ppm, respectively, at 24 and 48 h post treatment. Compounds 5 bearing 4-fluoro substituent on benzene ring and 9 carrying a 4-isopropyl group on the benzene ring were found to be the most active compounds in both bioassays. These results could be useful information for development of new effective fungicides and insecticides in the near future.