The large bugs arrived last week from Taiwan in a box whose contents were labeled as toys, gifts and jellies.
The postmaster suspected the package contained live organisms and notified authorities.
The package was sent to Philadelphia, where it was X-rayed and then opened.
A U.S. Customs and Border Protection agency spokesman said "They are highly destructive insect pests that can cause extensive damage to fruit and vegetable crops, trees, shrubs and turf grasses."
In all, authorities found 26 Hercules, rhinoceros and Goliath beetles. It is illegal to ship live beetles into the United States without a permit from the Department of Agriculture.
Seven of the beetles were in containers labeled by gender, which means they could have been intended for breeding.