Lemon Grass Oil

 When I was living in NTU in Singapore, I grew a lot of lemon grass. I couldn't use all of them, so my neighbours enjoyed them.

Apart from cooking curry, I also steep smashed up stems in hot water and drink tea.

Lemon grass also has insecticidal properties and the extracted oil is used in insect repellents and insecticidal sprays. 

 http://homeguides.sfgate.com/insecticidal-properties-lemon-grass-55229.html

Lemon Grass Oil

The oil of lemon grass is extracted from fresh or died lemon grass by steam distillation or simply by pouring boiling water over the foliage. The composition of lemon grass oil depends partly on geographical region or where it is grown. Major constituents of lemon grass oil are citral, geraniol, myrcene, citronellal and limonene. Citronella oil, which repels mosquitoes, contains large amounts of citral. Citral gives lemon grass oil its lemony fragrance.