Cymbopogon nardus L. is plant that can be utilized for its content, which is more abundant in the stems and leaves. This type of research is experimental, in which larvae receive treatment. Sampling was done by purposive sampling. The concentrations used in this study were 1.5 ml, 2 ml, 4 ml, 6 ml and 8 ml and the observation times used were 25 minutes, 45 minutes, 60 minutes and 90 minutes with 2 replicas. The results showed that citronella extract had a very high killing power against larvae which could be seen from the percentage of larvae mortality during the treatment test. The highest mortality of larvae occurred at a concentration of 8 ml/1000 ml of water in the 90th minute of the 2nd repetition with a total of 22 larvae deaths with a mortality percentage of 83%. This shows that citronella, both applied singly or in combination, has larvicidal effectiveness which is effective in killing Aedes aegypti larvae. The highest mortality of larvae occurred at a concentration of 8 ml/1000 ml of water in the 90th minute of the 2nd repetition with a total of 22 larvae deaths with a mortality percentage of 83%. This shows that citronella, both applied in combination, effectiveness which is effective in killing Aedes aegypti larvae. The highest death time was citronella extract with a concentration of 8 ml in the 90th minute. The highest mortality of larvae occurred at a concentration of 8 ml/1000 ml of water in the 90th minute of the 2nd repetition with a total of 22 larvae deaths with a mortality percentage of 83%.