Vector Control

Part of Sanitation and Hygiene

Disease vectors — organisms that carry pathogens from one host to another — have killed more humans throughout history than war, famine, and natural disasters combined. Without modern pesticides or pharmaceuticals, controlling vectors through environmental management, biological allies, and physical barriers is one of the most impactful things a settlement can do to prevent mass die-offs.

What Are Vectors?

A vector is any organism that transmits a disease-causing pathogen to humans without being the source of the disease itself. The mosquito does not make you sick — the Plasmodium parasite it injects into your blood does. The flea does not cause plague — the Yersinia pestis bacterium it carries does.

Major Vectors and Their Diseases

Vector	Diseases Carried	Transmission Method	Geographic Risk
Mosquito	Malaria, dengue, yellow fever, Zika, filariasis	Bite injects parasite/virus into blood	Tropics and temperate zones near standing water
Flea	Plague (bubonic/pneumonic), murine typhus	Bite deposits bacteria, or flea feces in wound	Anywhere with rodent populations
Body louse	Epidemic typhus, relapsing fever, trench fever	Feces rubbed into bite wound or skin abrasion	Crowded, unsanitary conditions
Housefly	Dysentery, cholera, typhoid, eye infections	Lands on feces, then on food or eyes	Universal — anywhere with exposed waste
Tsetse fly	Sleeping sickness (trypanosomiasis)	Bite injects parasite	Sub-Saharan Africa
Tick	Lyme disease, Rocky Mountain spotted fever, tick-borne encephalitis	Bite, pathogen transmitted after prolonged attachment	Wooded/grassy areas, temperate climates
Rodent	Hantavirus, leptospirosis, rat-bite fever	Urine/feces contaminate food/water, or bite	Universal — anywhere with poor food storage
Sandfly	Leishmaniasis	Bite injects parasite	Tropics, subtropics, Mediterranean

Flies Are Underestimated Killers

Mosquitoes get the attention, but common houseflies may cause more illness in a settlement context. A single fly can carry over 100 different pathogens on its body. One fly landing on uncovered food after visiting a latrine can transmit cholera, dysentery, or typhoid to everyone who eats that meal.

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Integrated Vector Management

Effective vector control uses multiple strategies simultaneously. No single approach eliminates all vectors. The framework has four pillars:

1. Environmental modification — change the habitat so vectors cannot breed
2. Biological control — use natural predators to suppress vector populations
3. Physical barriers — prevent vectors from reaching people
4. Chemical/botanical repellents — deter vectors from biting

Priority Order

Start with environmental modification. It requires the most labor upfront but provides permanent, self-sustaining results. Physical barriers are second — they protect individuals immediately. Biological control takes time to establish but runs on autopilot once in place. Repellents are a stopgap while the other systems mature.

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Environmental Modification

The most powerful vector control is denying vectors the conditions they need to breed and feed.

Against Mosquitoes: Eliminate Standing Water

Mosquitoes require standing water to breed. A female mosquito lays 100-200 eggs in as little as a bottle cap of stagnant water. Larvae hatch in 24-48 hours and become biting adults in 7-10 days.

Weekly sweep protocol:

1. Walk the entire settlement perimeter
2. Overturn, drain, or fill every container that holds water — pots, coconut shells, discarded vessels, tire ruts, animal troughs not in active use
3. Clear blocked drainage channels
4. Fill tree holes and ground depressions with soil or sand
5. Change water in any storage containers that cannot be covered — or cover them tightly

The 7-Day Rule

Mosquito larvae take 7-10 days to mature. If you empty every water container in your settlement once per week, no mosquito can complete its lifecycle within your perimeter. Make this a weekly chore assigned to a specific person or team.

Against Rodents: Remove Food and Shelter

Rodents need three things: food, water, and hiding places. Deny all three.

• Store all food in sealed containers — clay pots with fitted lids, tightly woven baskets lined with clay, or elevated platforms rats cannot climb (smooth poles, at least 1 meter off ground)
• Clean up food scraps immediately after meals — sweep cooking areas, collect dropped grain
• Clear brush and debris within 15 meters of shelters — woodpiles, leaf litter, and rubble provide nesting sites
• Seal gaps in shelter walls — rodents can squeeze through any opening larger than 2 cm

Against Flies: Cover Waste and Food

• Cover all latrines with fitted lids — a simple wooden board with a handle works
• Bury organic waste daily — compost pits must be covered with at least 10 cm of soil after each addition
• Cover food at all times when not actively eating — cloth covers, woven lids, inverted bowls
• Dry meat and fish thoroughly — flies are attracted to moist, protein-rich surfaces

Against Ticks: Clear Vegetation

• Cut grass and brush short within 30 meters of living areas
• Create a 1-meter gravel or wood-chip border between cleared camp and surrounding woods — ticks rarely cross dry, exposed ground
• Keep pathways clear — avoid brushing through tall grass when possible
• Check bodies daily during tick season — remove attached ticks by grasping close to the skin and pulling straight out with steady pressure

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Biological Control

Nature provides vector predators. Your job is to encourage them.

Mosquito Larvae Predators

Predator	Effectiveness	How to Use
Gambusia fish (mosquitofish)	Excellent — one fish eats 100+ larvae/day	Stock in permanent ponds, cisterns, irrigation channels
Guppies and other small fish	Good	Same as above — any small surface-feeding fish works
Dragonfly larvae	Good	Maintain pond margins with emergent vegetation; dragonflies colonize naturally
Tadpoles (some species)	Moderate	Frogs colonize naturally near water; avoid disturbing them

Fish in Water Storage

If you store water in open tanks or cisterns that cannot be covered, add small fish. They will eat every mosquito larva that hatches. One or two fish per 100 liters is sufficient. The fish do not contaminate the water for drinking — filter or decant as you normally would.

Rodent Predators

• Cats — a single semi-feral cat can eliminate rodents from a grain store. Do not overfeed the cat — a well-fed cat still hunts, but a hungry one hunts more
• Barn owls — attract by installing nesting boxes (a simple wooden box with a 10 cm entrance hole, mounted 3+ meters high). A breeding pair of barn owls consumes 3,000+ rodents per year
• Snakes — non-venomous snakes near food storage areas should be tolerated, not killed. They are efficient rodent hunters

Fly Predators

• Parasitic wasps (tiny, non-stinging species) lay eggs in fly pupae — they occur naturally and can be encouraged by avoiding broad-spectrum pest control that kills them
• Spiders — leave webs intact near latrine and cooking areas. A single web can catch dozens of flies per day
• Chickens — free-ranging chickens eat flies, ticks, and other insects aggressively

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Physical Barriers

When you cannot eliminate vectors, block them from reaching people.

Bed Nets

The single most effective physical barrier against mosquitoes. See Mosquito Prevention for detailed construction and use.

• Mesh size must be smaller than 1.5 mm to exclude mosquitoes
• Tuck under sleeping mat or bedding — no gaps
• Inspect for holes weekly; patch immediately

Window and Door Screens

• Weave fine mesh from plant fibers, hair, or thin strips of bark — openings must be under 2 mm
• Frame the mesh in a wooden frame sized to your window opening
• For doorways, hang two overlapping mesh panels that the person parts when entering — they fall closed by gravity

Fly Covers for Food

• Woven mesh domes placed over food dishes
• Cloth covers weighted at the edges with small stones
• Elevated food platforms with smooth legs that flies can land on but ants cannot climb

Clothing as Barrier

• Long sleeves and long trousers during dusk and dawn (peak mosquito hours)
• Tucked trouser cuffs in tick-prone areas — tuck into boots or tie with cord
• Light-colored clothing — makes ticks visible before they reach skin; also attracts fewer mosquitoes than dark clothing

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Natural Repellents

Without commercial insecticides, plants provide your repellent toolkit.

Effective Plant-Based Repellents

Plant	Active Compound	How to Use	Effective Against
Citronella grass	Citronellal	Crush leaves, rub on skin; burn dried leaves	Mosquitoes
Neem (leaves/oil)	Azadirachtin	Crush leaves into paste for skin; burn leaves	Mosquitoes, flies, ticks
Eucalyptus	Cineole	Crush leaves, apply oil to skin; hang branches	Mosquitoes
Lavender	Linalool	Rub flowers on skin; place dried bundles near beds	Mosquitoes, fleas, flies
Mint/pennyroyal	Pulegone	Crush and rub on skin; scatter around food areas	Flies, fleas, rodents
Pyrethrum (chrysanthemum)	Pyrethrins	Dry flowers, grind to powder, burn as smoke	Mosquitoes, flies, fleas, ticks
Smoke (any wood)	Particulates	Maintain a smoldering fire near gathering areas	Mosquitoes, flies

Reapply Every 2-3 Hours

Plant-based repellents evaporate quickly. Unlike synthetic DEET, which lasts 6-8 hours, crushed citronella or neem paste provides effective repellency for only 2-3 hours. Reapply frequently, especially during peak biting times (dusk and dawn for mosquitoes, midday for flies).

Smoke as a Vector Deterrent

Smoke is the oldest and most universally available repellent. A smoldering fire (not a roaring blaze — you want smoke, not heat) near sleeping and eating areas drives away mosquitoes, flies, and gnats effectively.

• Use green wood or damp leaves to produce thick smoke
• Position the fire upwind of the area you want to protect
• For sleeping, a small smudge pot (clay bowl with smoldering coals and damp plant matter) inside the shelter works — ensure adequate ventilation to prevent carbon monoxide buildup

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Settlement-Wide Vector Control Plan

Assign these roles and schedules to make vector control systematic rather than reactive.

Task	Frequency	Assigned To
Standing water sweep	Weekly	Water team
Food storage inspection (rodent signs)	Weekly	Cooks / food managers
Latrine lid check + fly inspection	Daily	Sanitation team
Bed net inspection and repair	Weekly	Each household
Brush clearing (30m perimeter)	Monthly	Work crew
Tick checks (all residents)	Daily in season	Each individual
Repellent plant harvest and preparation	Weekly	Designated gatherer
Rodent trap check and reset	Daily	Designated trapper

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Key Takeaways

1. Environment first. Draining standing water, sealing food stores, and covering waste eliminates more vectors than any trap or repellent.
2. Flies kill through food contamination. Cover every latrine, bury every scrap, and protect every meal.
3. Biological allies are free and self-sustaining. Fish eat larvae, cats hunt rodents, chickens devour ticks and flies. Encourage them.
4. Physical barriers work 24/7. Bed nets, window screens, and covered food require no resupply.
5. Repellents are temporary. Use them, but do not rely on them as your primary defense.
6. Make it systematic. Assign tasks, set schedules, inspect results. Ad hoc pest control fails; organized programs succeed.