Stable Fly
Stomoxys calcitrans
Viral Vectors High Risk 5–7 mm (adult); 8–11 mm (mature larva)
📖 Description
Stomoxys calcitrans, the stable fly or dog fly, is a major biting fly pest of livestock globally. Unlike the housefly, both male and female stable flies feed exclusively on blood — they require a blood meal every 1–2 days and each feeding takes 2–5 minutes. The species is a particular problem in Indian dairy production (estimated 300 million cattle and buffalo), where stable fly attack causes annual losses of ₹4,000–6,000 crore through reduced milk production and reduced weight gain. The species is also a major pest of horses, pigs, and dogs. Stable flies are strong fliers — they can disperse up to 25 km in search of hosts — but typically remain within 5 km of their breeding site. The species is most abundant in moist, fermenting organic matter such as straw bedding contaminated with urine and faeces, silage, hay, and grass clippings — hence the common name ‘stable fly’. Multivoltine, with continuous overlapping generations in warm conditions.
⚠️ Symptoms to watch for
- Painful bites (more painful than mosquito bites — the fly's mouthparts are scissor-like and tear the skin); persistent attack on cattle legs causes bunching, stamping, and tail-switching; reduced milk production of 10–30 % in dairy cattle under heavy fly pressure (≥50 flies per animal); reduced weight gain of 0.1–0.3 kg/day in feedlot cattle; persistent attack on horses causes behaviour problems and riding difficulty; stable flies are mechanical vectors of Trypanosoma evansi (surra), equine infectious anaemia virus, anthrax, and pasteurellosis; bite wounds can become secondarily infected.
🩹 Treatment
- Apply pour-on deltamethrin 1 % or permethrin 5 % on cattle at 14-day intervals during fly season. Use permethrin 10 % WP as a surface spray on stable walls and resting sites. Apply cypermethrin 5 % as a mist spray in stables. Use baited traps (Alsynite cylinder traps) at 4 per dairy facility for adult fly monitoring and mass-trapping. Apply methoprene 1 % as a feed-through larvicide in cattle mineral licks.
🌿 Organic treatments
- Manage breeding sites: remove and compost soiled straw bedding weekly; store hay and silage under cover; prevent moisture accumulation in feed storage. Apply Bacillus thuringiensis var. israelensis (Bti) at 1 g/m² to moist breeding media. Release parasitic wasps (Spalangia cameroni, Muscidifurax raptor) at 50 per m² of breeding media. Use essential oil repellents (citronella, eucalyptus, lemongrass) on horse coats. Install Alsynite traps at 4 per dairy facility.
🧪 Chemical treatments
- Deltamethrin 1 % (pour-on for cattle), permethrin 5 % (pour-on for cattle), permethrin 10 % WP (surface spray for stables), cypermethrin 5 % (mist spray for stables). Apply at 14-day intervals during fly season. Rotate chemical classes to prevent resistance development.
🛡️ Prevention
- Manage moisture: maintain dry bedding in stables and dairy houses; repair leaky waterers; ensure drainage. Remove and compost soiled bedding weekly. Store hay and silage under cover. Clean up spilled feed and forage promptly. Use fans in stables — stable flies are weak fliers and air movement >3 m/s deters them. Screen stable windows with 1 mm mesh. Use dark-coloured Alsynite traps at 4 per facility.
🪴 Affected plants
- Not a plant pest — both sexes feed on blood from mammals (cattle, horses, pigs, dogs, humans). Larvae develop in decomposing organic matter, particularly moist, fermenting vegetation — straw bedding, hay, silage, grass clippings, manure with bedding, seaweed on beaches.
🦋 Natural predators
- Predatory mites (Macrochele muscaedomesticae), predatory beetles (Carcinops pumilio), parasitic wasps (Spalangia cameroni, S. nigroaenea, Muscidifurax raptor), spiders (Theridiidae, Salticidae), and birds (swallows, flycatchers). Fungal pathogens (Entomophthora muscae, Beauveria bassiana) cause significant mortality in humid conditions.
🌱 Host plants
- Not a plant pest. Larvae develop in moist decomposing organic matter — straw bedding contaminated with urine and faeces, silage, hay, grass clippings, seaweed on beaches, manure with bedding, and compost.
🔄 Lifecycle
- Egg (1–3 days, laid in batches of 25–50 in moist breeding media) → Larva (8–20 days, 3 instars) → Pupa (5–10 days, in dry soil near breeding media) → Adult (20–30 days, females lay 200–400 eggs).
- Multivoltine — 5–7 overlapping generations per year in tropical India; 3–4 generations per year in temperate India.
📅 Season
- Active throughout the year in tropical south India; peak activity June–October (monsoon and post-monsoon).
- In north India, peak activity May–September; inactive December–February in cold winters.
- Populations can explode after wet weather that produces moist breeding media.
🔎 Appearance
- Adult resembles the housefly but is slightly larger and greyer; the most diagnostic feature is the prominent forward-projecting piercing-sucking proboscis (visible from above); the thorax has four dark longitudinal stripes (similar to housefly but slightly less distinct); abdomen has three dark circular spots on the second and third segments; wings are transparent with a sharp forward angle.
- At rest, stable flies often hold their wings 'roof-like' over the body and prefer to rest on vertical surfaces.
- Larvae are whitish maggots similar to housefly larvae but with a more rounded posterior.
💥 Damage level
- Severe
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Cosmopolitan in livestock production worldwide. In India
- common across all states with significant livestock production; particularly damaging in dairy belts (Gujarat — Anand
- Banaskantha; Punjab — Ludhiana
- Bathinda; Maharashtra — Kolhapur
- Nashik; Tamil Nadu — Erode
- Salem; Karnataka — Hassan
- Mandya) and horse-breeding areas (Punjab
- Haryana
- Rajasthan).
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