I was looking at this site;
http://www.health-marketplace.com/Lemon-grass.htmAnd this is there;
Lemon Grass Oil Properties - Analgestic, anti-depressant, antimicrobal, anti-oxidant, antipyretic, antiseptic, astringent, bactericidal, carminative, deodorant, febrifuge, fungicidal, galactagogue, insecticide, nervine, sedative (nervous), tonic.
Did you see that word "insecticide"?