Adoptions are on hold for thousands of dogs and cats in Texas, potentially putting the animals at risk of being euthanized, because of efforts to stop the spread of the New World screwworm, an insect that has crossed the border from Mexico into the United States for the first time in 60 years.

The flesh-eating parasite threatens the nation's $113 billion beef industry, prompting federal officials to close the border to cattle movements.

Because the screwworm also can infect pets, most states have restricted the movement of animals from infested areas of Texas, leading to crowded conditions in state shelters that rely on adoptions to other regions of the country.