A cache of about 90 live snails — considered an invasive species that can damage crops, homes and human health — was seized by United States Customs and Border Protection (CBP) officers at the Detroit airport last month, the agency says.

According to a CBP news release, 90 Giant African snails were discovered in a passenger's luggage on June 30 when they were arriving from Ghana. 

The passenger had been sent to secondary screening after declaring fresh food items and an agriculture specialist noticed a tied, woven bag in the luggage. 

"Inside the bag were Giant African Land snails ranging from three to six inches in length," the agency said in a statement.

"Prior to the luggage being opened, the passenger began declaring other prohibited items, such as beef skin and fresh peppers, but there was no mention of the snails, which are considered an invasive species in the U.S."

CBP seized the snails, which were intended for consumption. 

According to the news release, the snails have a "voracious" appetite and "cause major crop damage when they escape into the environment."

"They can also pose a public health threat to humans. The snails can grow up to eight inches and feed on a wide variety of plants, including many economically important crop plants, and cause structural damage by using stucco on houses to meet their calcium requirement for shell growth."

Travellers are asked to review all current regulations before travelling with fresh food items.