Old World screwworm fly

Systematic position: Chrysomya bezziana belongs to the order Diptera, family Calliphoridae. It is a highly dangerous species of obligate parasite known for causing traumatic myiasis in warm-blooded animals, including livestock and occasionally humans.

Affected hosts: While this species does not damage crops, it is a significant pest in the livestock sector. Primary hosts include cattle, sheep, goats, horses, and dogs. The pest targets animals that have any form of open wound, skin lesion, or natural body orifice where they can deposit eggs.

Biology and life cycle: Adult flies do not feed on host tissues, but females lay eggs in clusters within or near existing wounds. Larvae hatch within 12–24 hours and begin to feed aggressively on live host tissue, burrowing deep into the animal's body. The larval development stage lasts between 5 to 7 days, after which they exit the wound, drop to the ground, and pupate.

Nature of damage and economic impact: The feeding activity of the larvae leads to severe secondary bacterial infections, deep muscle damage, and tissue necrosis, which can be fatal if left untreated. Affected animals experience loss of appetite, rapid weight loss, and a significant drop in productivity, such as milk yield or fleece quality.

Control measures: The primary management strategy involves prevention and rapid veterinary intervention.

• Regular inspection of livestock for wounds or signs of infestation.
• Prompt treatment of all wounds with antiseptic and insecticidal agents.
• Utilization of effective repellents during the fly's peak activity periods.
• Sanitary disposal of carcasses and elimination of potential fly breeding sites.