 Plants will be evaluated under natural user conditions in a randomised and controlled manner in villages in Xishuangbanna Region, Yunnan, PR China. Village- based studies of several other mosquito control methods have already been successfully undertaken in this region by the LSHTM and YIPD team. Villages belonging to one of the ethnic groups using each traditional method will be selected according to agreement between local health workers from YIPD and the village elders, availability of plant species, and preliminary survey of vector species collected indoors with CDC traps. A different village will be selected for each plant being evaluated. After collecting background entomological data, 6 houses matched for baseline parameters such as occupancy level, location, construction animal proximity and being evenly spaced among others in the village to reduce diversion effects will be enrolled into the study. On any one night, 2 will be allocated treatment use of plant, 2 will be allocated hay used for cattle bedding as a negative control, and 2 will be left unused to reduce any residual effects. In each case the treatment or control group will be instructed to place pre-prepared batches of plant material weighed fresh or dry depending upon type onto their cooking fire in the traditional manner in the early evening. Commercial CDC traps BioQuip Inc., USA will be used in beside the sleeping areas of each house from 1 hour before sunset to early morning. Catches will be identified by local vector experts each day to record species and number. House treatment will be rotated each night using latin square principles to achieve a minimum of 12 replicates of each treatment in every house 36 nights duration, 216 trapnights, and will take place during the rainy malaria season July - Nov 2005 when both plants and vector levels are highest. 