Although increased use of insecticide-treated mosquito nets and indoor residual spray has significantly reduced the number of malaria cases, these efforts are tempered by the development and spread of insecticide resistance among the main vectors of malaria1. Currently, DDT and synthetic pyrethroids are widely used for indoor waste spraying and solely for insecticide-treated bed nets in all malaria-endemic countries, including India, which insists on the absolute need for regular monitoring of insecticide resistance in mosquito vectors. Anopheles (Cellia) annularis Van der Wulp is widespread in Asia and is considered an important vector of malaria in India and neighboring countries1-2. In the northeastern states, An. annularis is abundant and has recently been suggested to be an important vector of malaria in addition to An. minimum and An. dirus2-3. The continuous and indiscreet use of DDT for indoor residual spray (IRS) has led to the development and spatial spread of physiological resistance among many efficient malaria vectors in India4-6. Furthermore, the use of synthetic pyrethroids in insecticide-impregnated mosquito nets (ITNs) and long-lasting insecticidal mosquito nets (LLINs) has led to the development of resistance in some known mosquito vectors5-6. Although metabolic mechanisms play an important role in conferring resistance to pyrethroids, behavioral changes in the mosquito vector population could impact the effectiveness of insecticides7. Insecticide resistance is a dynamic phenomenon, and the level of resistance among mosquito species differs even among neighboring areas8. Therefore, extrapolation of insecticide resistance results from one geographic area to another may be inappropriate. In addition to monitoring An's......middle of paper......er. annularis was found feeding on human blood, indicating that this malaria support vector may be shifting its dietary preference from animals to humans. A specimen of An. annularis was detected positive for P. falciparum infection. A recent study conducted in Assam showed that 14.3% of human blood fed with An. annularis mosquitoes were positive for Plasmodium2 infection. However, the current findings do not purport to incriminate An. annularis as a vector of malaria, but provide compelling evidence that it may be a vector of malaria in the study area. The present study, although including a small sample size, provides important information on vector control and transmission of malaria in an area that is difficult to access and frequently subject to ethnic conflict. Furthermore, this adds to the limited data available on behavioral resistance of malaria vectors in India.