For Reference ...
U.S. Customs and Border Protection Declaration Form 6059B - Instructions
http://www.cbp.gov/xp/cgov/travel/va...ation_form.xml
11. Mark an X in the Yes or No box. Are you bringing with you:
a. fruits, plants, food, or insects?
b. meats, animals, or animal/wildlife products?
c. disease agents, cell cultures, or snails?
d. soil or have you visited a farm/ranch/pasture outside the United States?
12. Mark an X in the Yes or No box. Have you or any family members traveling with you been in close proximity of (such as touching or handling) livestock outside the United States?