insidious

in·sid·i·ous

adj.

1. Working or spreading harmfully in a subtle or stealthy manner: insidious rumors; an insidious disease.
2. Intended to entrap; treacherous: insidious misinformation.
3. Beguiling but harmful; alluring: insidious pleasures.

Two kinds of political corruption blight India: episodical and ongoing. Episodical corruption - from 2G spectrum to rice exports - has cost the public exchequer possibly over Rs 1,00,000 crore this year. The sum could have wiped out a quarter of India's 2010-11 fiscal deficit of Rs 4,12,000 crore. Ongoing corruption is more insidious and, therefore, more damaging.