Be on the lookout for deadly screwworm infestations in livestock.

Florida Ag Commissioner, Bob Crawford, is asking all animal owners, private veterinarians and the general public to be on the lookout for screwworm. Screwworm is the common name of a pest native to the tropical areas of North, South and Central America that causes extensive damage to domestic livestock and other warm-blooded animals. The larvae of these pests feed on the raw flesh of the host animal and can grow to be more than half an inch in five to seven days. Rare human cases have been reported.

They ask anyone finding a suspicious larvae to contact the state's Veterinarian's Office: 1-877-815-0034 or USDA's veterinarian in charge at 1-800-342-0395.

The US has been free of screwworm since 1966. Limited screwworm outbreaks in Mexico during 1992-93 were contained and eradicated. Eradication efforts are ongoing in Jamaica at this time.

This first screwworm case was discovered by a vet in Wellington, Florida in March, 2000 on a horse imported from Argentina.

When larvae drop from a wound, they burrow into the soil where they enter the pupal stage, which lasts five to seven days. Adult flies emerge from the pupal cases and are ready to mate within three to five days. The adult is about twice the size of the common housefly. It has orange eyes and a blue-gray or gray body with three dark stripes running down its back.

After mating, the female screwworm fly lays her eggs in the open wounds of animals -- up to 400 at a time. These eggs hatch into larvae in as little as 12 hours.

Initial cases of screwworm are often detected in pets. The eggs hatch in a wound of an animal and the larvae feed off the animal's flesh. Animals may die within days.

Infestation is treated with topical application of approved chemicals to kill the larvae. The larvae should be removed from the wounds using tweezers.

An approved organophosphate insecticide will provide protection against screwworm for seven to 10 days. However, the best way to control screwworm infestation is through eradication.

What to look for

1. Wounds that may become infested with maggots. (Navels of newborns, castration, dehorning, branding, shearing, wire cuts, sore mouth in sheep, etc. It's very hard to see them in the early stages -- only a slight movement may be noticed. As they feed the wound will become wider and deeper. In some cases, the openings in the skin may be minute, with extensive pockets of larvae beneath.)

2. Bloody discharge from the infested wounds.

3. Distinctive bad odor.

4. Discomfort.

5. Decreased feed intake.

6. Decreased milk production

7. Seclusion from the rest of the herd -- animals may seek shady or secluded areas to lie down.

Animals infected with screwworm may die in seven to 14 days if wounds are not treated to kill the larvae, especially in cases of multiple infestations. As many as 3,000 larvae may be found in a single wound. Death results from toxicity and/or secondary infection.

A fact sheet about screwworm is available at: www.aphis.usda.gov/oa/ pubs/fsscworm.html