The present work has been attempted to work out the isolation and characterization of a terpenoid from a major host plant Butea monosperma of Indian lac insect (Kerria lacca), and its probable impact on the degenerative growth pattern of the female morph, which losses its legs and antennae in its adult stage. The studied terpenoid (C30H52O) as ingested from the host plant by the female K. lacca probably plays a key role by inhibiting the acetylcholinesterase (AChE, EC 126.96.36.199) undergoing the process of uncompetitive inhibition. This type of inhibition is supported by bio-informatics studies also. This inhibition of AChE may be one of the responsible factors for the degenerative growth pattern of female K. lacca featuring the loss of all locomotory organs (legs) and antenna, etc. This is most probably caused by the rapid deacceleration of the molar hydrolysis of substrate acetylcholine by the enzyme AChE under such uncompetitive inhibition by the terpenoid as studied.