You Do Need power plug adapter while traveling from United States Virgin Islands to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in United States Virgin Islands are A and B. This is how they look like.

United States Virgin Islands

In United States Virgin Islands, outlets of type A and B are in use.

Type A

Type B

Sri Lanka

In Sri Lanka, outlets of type G are in use.

Type G