Raxsina Polseela 1*, Apichat Vitta 1, and Chamnarn Apiwathanasorn 2 1 Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand 2 Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. 1* Corresponding author: Thank you to Head of Tham Chaoram Wildlife Sanctuary, Sukhothai and staff, sand flies and insects. This study was financial supported from The Higher Education Research Promotion Congress and Naresuan University. Apiwathanasorn,C., Sucharit,S., Rongriyam,Y.,et al.(1989). A brief survey of Phlebotominae sand flies in Thailand. Southest Asian J Trop Med Public Hlth.20: Fahmy, AR., et al.,(2009). Preliminary field investigations on Phlebotomine sand flies (Diptera: Psychodidae) from a recent cutaneous leishmaniasis focus in Northern-Sinai, Egypt.Egypt. Acad. J. biolog. Sci., 2(1): 9 – 15. The main objective was to investigate the species of the phlebotomine sand fly inside and outside cave. P. argentipes (3.95%) S. anodontis (47.19%) The sandflies of the study area include species previously found in Thailand. The sand fly, P. argentipes was found only inside cave, which is important because it is believed to be the Leishmania spp. vector. The most predominant female sandflies was S. silvatica (outside cave) and S. anodontis (inside cave). This suggests that phlebotomine sand flies show nocturnal flight activity. The population dynamic of sandflies in Chao Ram cave was greatly affected by several enviromental conditions such as temperature, humidity, rainfall and wind velocity. The widespread distribution of sand flies may be an indicator of the epidemiologic importance of the vector sand flies in this habitat. An investigation of the species of the phlebotomine sand fly was conducted from August 2011 to August Sand flies were collected by CDC light traps from inside and outside Chao Ram Cave, Sukhothai and collection 15 light traps per month per locations. Sand flies (Diptera: Psychodidae: Phlebotominae) are considerable public health importance in the tropics and subtropics. They are obligate vectors of Leishmaniasis, a protozoan disease that affects people in more than 80 countries. P. argentipes Figure 1 Shape of cibarium and spermatheca of sand flies Maximum Inside cave Maximum Outside cave Vector Inside cave: (important) Inside cave, a total of 13,750 sand flies were collected (11 species). The ratio between male and female sand flies was 1:1 (6,960:6,790). Outside cave, 2,378 sand flies were collected (12 species) and ratio 1:1.76. The highest numbers of sand flies were found inside cave. In this study, 14 species were identified by morphology as : Phlebotomus argentipes, P. stantoni, P. teshi, P. philippinensis gouldi, Sergentomyia barraudi, S. anodontis, S. dentata, S. perturbans, S. iyengari, S. quatei, S. silvatica, S. gemmea, S. indica, and Chinius barbazani, unidentification 4 species (a,b,c,d) The highest peak of sand flies found in April (inside cave) and June (outside cave). S. silvatica (44.69%) C. barbazani