Aedes aegypti is the main vector mosquito for transmitting Zika virus, which causes congenital 
microcephaly and other debilitating conditions. This study assessed the larvicidal and synergistic 
activities of Lemon eucalyptus stem extracts against the 4th instar larvae of Ae. aegypti. Stem 
samples were collected, dried, powdered, and extracted using methanol, hexane, ethyl acetate, 
and acetone. About 64.3% of the extracts caused moderate larvicidal activity after 24 hours. 
Hexane and acetone extracts showed the highest activity at 1000ppm. The extracts contained 
saponins, tannins, steroids, flavonoids, alkaloids and resins. Synergistic studies revealed moder
ate larvicidal activity for all combinations of extracts at different concentrations.  Lemon euca
lyptus stem extracts have promising larvicidal and synergistic activities against Ae. aegypti as a 
safe effective way to stop Zika virus transmission.