An apparatus was designed and fabricated for studying the effects of aromatic chemicals on the IV instar larvae of Aedes aegypti (L.). The test chemicals (essential oils and monoterpenoids) were incorporated in agar along with yeast and dog biscuits which formed an attractant food source (bait). A fairly rapid decrease in the migration of larvae towards the bait cum chemical source was observed during the first hour after which a steady state was observed. Minimum migration (9.67%) was seen with terpeneol anhydrous and maximum (15.0%) with beta-citronellal as compared to control (65.67%), at the end of a 4 hr exposure period. Food particles were also detected on microscopic examination.