Ticks are parasitic haematophagus arthropods playing a major role in disease transmission among human and animals. Effective tick control is mainly accomplished through widespread use of chemical acaricides, which have a negative impact on environment, humans, and animals due to their toxicity and indiscriminate use leads to resistance developement. So, there arise an essentiality for development of safer, eco-friendly methods for control of acarine parasites. The present study was conducted to identify phytochemicals in methanolic extract of leaves of Cleistanthus collinus. and its acaricidal activity against Haemophysalis bispinosa. Leaves of C. collinus were harvested at the College of Veterinary and Animal Sciences Mannuthy campus in Thrissur, Kerala, India. They were shade-dried, ground into a powder, and extracted using methanol. A rotary vacuum evaporator was used to concentrate extract, and FTIR, GCMS, and qualitative phytochemical screening were carried out. Acaricidal activity was determined by adult immersion assay by accounting for various entomological parameters such as per cent adult mortality, index of egg laying and percent inhibition of fecundity using various concentrations of extract. Phytochemical analysis detected presence of steroids, alkaloids, glycosoides, flavonoids, terpenoids, in methanolic extract of C.collinus leaves. GC–MS analysis confided presence of Dianhydromannitol,Diethyl phthalate, Cyclooctasiloxane, Benzophenone, Dodecanoic acid, Tetradecanoicacid, Hexadecenoic acid, among many compounds. FTIR analysis ascertained presence of various functional groups like aldehydes, sulfoxides, phenol, vinyl ether and aliphatic ketones. There was cent per cent mortality of ticks in all doses tested. Index of egg laying was found to be zero and maximum inhibition of fecundity was observed in higher concentrations. IC50 found to be 30.84 mg/mL. From results, it was clear that methanolic extract of leaves of C.collinus induced very early adult tick mortality. It was apparent that methanolic extract of C.collinus leaves flaunted potent acaricidal activity against H. bispinosa and can be used to develop a potent ectoparasiticide.