Outside groups spent $1.51 million on trips for members of Congress during the first three months of 2014, a dip from the same period last year, according to data compiled by LegiStorm.

More than half of the first quarter's total was spent in February, marking the busiest month — excluding traditionally travel-heavy August — in more than eight years.

Private sponsors spent $1.63 million on congressional trips during the first quarter of last year — the highest first quarter since a series of scandals prompted Congress to pass reforms in 2007 that limited lobbyists' ability to fund travel, said LegiStorm, a Congress-focused research group.

Rep. Mike McIntyre, D-N.C., a House Armed Services Committee member, and his wife in February took the most expensive privately sponsored trip on record, LegisStorm said: a week in Adelaide, Australia, paid for by Defence Teaming Centre Inc., an Australian defense industry nonprofit group. The cost was $49,635.

The second-most expensive trip was taken by Rep. John Garamendi, D-Calif. His trek to Tanzania and the Sudan cost $40,083.