INTRODUCTION Essential oils extracted from aromatic plants have been used since ancient times as safe condiment or spice, in flavour and fragrances in medicines and to combat against microbes and to prevent or keep stored agricultural products safe from insects 1-4 . Essential oils are successful alternatives to insecti- cides without causing any danger to the environment 5-7 . Biolo- gical compounds with improved insecticidal properties and being non-toxic or only mildly toxic to humans are needed on constant basis 2 . Microtermes mycophagus (Desneux) is a subterranean termite species that infests commercially important timber species like Dalbergia sissoo, Cedrus deodara, Mangifera indica, Zyziphus spp, Morus spp. and Acacia spp, attacking logs and stumps, causing a lot of damage to forests, wooden structures and buildings. This species has also been reported as agricultural pest of nurseries, vegetables and sugarcane field 8-11 . Essential oil obtained from the leaves of Eucalyptus citriodora belonging to the family Myrtaceae, is used as a pesticidal agent and as insect repellent 12 . Lemon grass ( Cymbopogon citratus), member of family Poaceae (Gramineae), is a local grass native to India, Sri Lanka and Pakistan. Chemical Composition of Essential Oils Derived from Eucalyptus and Lemongrass and Their Antitermitic Activities Angainst Microtermes mycophagus (Desneux). FARKHANDA MANZOOR 1,* , NARJIS NAZ 2 , SAADIYA A. MALIK 1 , SAMRA ARSHAD 1 and BINA SIDDIQUI 3 1 Department of Zoology, Lahore College for Women University, Lahore, Pakistan 2 Department of Chemistry, Lahore College for Women University, Lahore, Pakistan 3 HEJ Research Institute, Karachi, Pakistan *Corresponding author: E-mail: doc_farkhanda@yahoo.com (Received: 27 December 2011; Accepted: 7 November 2012) AJC-12369 The essential oils of eucalyptus (Eucalyptus citriodora) and lemon grass (Cymbopogon citratus) were analyzed by GC-MS and tested against economically important termite species of Pakistan i.e., Microtermes mycophagus (Desneux). Their physical parameters were also scanned. The major constituents identified in eucalyptus oil are: eucalyptus, limonene, terpinen-4-ol, gravenone, n-tetradecane, 2,2′6,6′- tetramethyl piperidin-4-ol, piperitone and the chemical components of lemon grass oil are: myrcene, citronellol, citral, nerol and neric acid. The repellency, toxicity, fumigation activities of test oils and tunneling behaviours of M. mycophagus were evaluated. At 25 μg/10μL oil concentration, lemon grass showed 63.33 % and eucalyptus oil showed 62.22 % mortality and at the same concentration, the repel- lency test revealed that both eucalyptus and lemon grass oils showed efficient repellency i.e., 42.6 and 36.33 % respectively. Fumigation results revealed that lemon grass caused 100 % mortality at 5 ppm concentration on 9 th day of treatment whereas eucalyptus gave same result in the end of test period (day 12). When tunneling behaviour was observed for M. mycophagus, the average time to cross the tube at 50 μg was 28 and 50 h in eucalyptus and lemon grass oil one-to-one. Key Words: Anti-termitic activity, Eucalyptus, Lemongrass, Microtermes mycophagus (Desneux). The present study is the continuation of our research work 13 to test the different essential oils as potential termiticides and to detect the constituent profile of these oils by GC-MS, so eucalyptus and lemon grass oils are assessed as insect repellent, toxicant and fumigant against M. mycophagus (Desneux). EXPERIMENTAL Test essential oils: Reverse Dean-Stark method was used for steam distillation of the essential oils from the leaves of E. citriodora and C. citratus. The percentage yield of each essential oil was determined. Oils were also tested for physical parameters such as solubility, specific gravity, refractive index, acid value and ester value. GC-MS analysis: GC-MS of Varian, Saturn model 2000, equipped with ion trap detector (ITD) was used for the detection of various components of essential oils. Sample was injected on a DB-5MS (30 m × 0.25 μm id, 0.25 μm film thickness) column. Helium (carrier gas) with a flow rate of 1.0 mL/min and split ratio 1:5 was used. The temperature of column was maintained at 50 ºC at start for 3 min with a 4 ºC rise/min to Asian Journal of Chemistry; Vol. 25, No. 5 (2013), 2405-2408 http://dx.doi.org/10.14233/ajchem.2013.13335