Abstract: Twenty kinds of extracts from 8 species of Asteraceous plants were tested for their light-activated toxicities against mosquito larvae in the conditions of the presence and absence of near-UV light.The results showed that the extracts from Tagetes erecta were highly phototoxic:The methanol extract,ethanol extract,both obtained by maceration, and the petroleum ether extract from the root,whole plant and the flower caused 100% of mortality to the fourth instar larvae of Aedes albopictus at the concentration of 0.1 g/L in the presence of near UV light while the mortalities caused were 70%,20% and 0 respectively in the absence of near- UV light. Similar results were obtained on performing the experiment with the fourth instar larvae of Culex quinquefasciatus .It was noteworthy that the methanol extract, obtained by Sohxlet method from the root was effective in either the presence or absence of near-UV light and caused 100% of mortality in the concentration of 0.1 g/L under both conditions.