Published March 22, 2026

Eco-Friendly Automated Mosquito Trap - Arduino Nano

Garden pool attracts mosquitoes to lay eggs, then auto-flushes before they hatch. No chemicals - just an Arduino, a pump, and a timer.

BeginnerFull instructions provided1 hour53

Eco-Friendly Automated Mosquito Trap - Arduino Nano

Things used in this project

Hardware components

Arduino Nano Every

Maxim Integrated DS3231MPMB1 Peripheral Module

DFRobot Solar Power Manager 5V

Battery, 3.7 V

Seeed Studio 5V Relay module (digital) Electronic Brick

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)

Wire Stripper & Cutter, 18-10 AWG / 0.75-4mm² Capacity Wires

Digilent Mastech MS8217 Autorange Digital Multimeter

Multitool, Screwdriver

Story

The Problem

Mosquitoes lay their eggs in standing water. A farmer near me taught me a trick: if you let the eggs develop but flush the water before they hatch into adults, you wipe out the next generation. Repeat every 4 days for a few weeks and the local population drops to almost nothing.

I set up a small garden pool to attract them. The problem? You have to drain and refill the water every 4 days. Miss a cycle and you're actually breeding mosquitoes. My wife was not happy when I forgot twice.

So I automated it with an Arduino Nano. No chemicals. No citronella. No bug zappers. Just water and timing.

How It Works

The system runs on a simple 4-day cycle:

Timer triggers every 96 hours
Relay 1 activates → 5V submersible pump drains the pool until the float switch reads LOW
Short delay (30 seconds)
Relay 2 activates → 12V solenoid valve opens, pool refills until float switch reads HIGH
System sleeps until next cycle

The mosquitoes are attracted to the standing water and lay eggs. Before the larvae can mature into adults (~4 days), the water is flushed and replaced. After a few weeks, the breeding cycle is broken and the population crashes.

Circuit Overview

This is a multi-voltage system running off a single 12V power supply:

12V rail: Powers the solenoid valve directly through Relay 2

5V rail (via LM2596 buck converter):

Arduino Nano (5V pin)
Relay module logic
Submersible pump (through Relay 1)

Signal connections:

Float switch → Arduino digital pin (with internal pull-up)
Arduino digital pins → Relay module IN1 and IN2

Important: Adjust the buck converter potentiometer to output exactly 5V BEFORE connecting the Arduino. Sending 12V to the Nano will fry it. Learned that one the hard way.

Step-by-Step Assembly

Step 1: Prepare the power supplyConnect the 12V power supply to the DC barrel jack adapter. Wire the positive and negative outputs to two rails: one goes directly to the relay module's COM2 terminal (for the solenoid valve), the other goes to the LM2596 buck converter input.

Step 2: Set up the buck converterBefore connecting anything else, power on the 12V supply and adjust the LM2596 potentiometer with a small screwdriver until the output reads 5.0V on a multimeter. This powers everything except the solenoid valve.

Step 3: Connect the Arduino NanoWire the 5V output from the buck converter to the Nano's 5V pin (not VIN). Connect GND to GND.

Step 4: Wire the relay module

Connect 5V and GND from the buck converter to the relay module's VCC and GND
Arduino digital pin → Relay IN1 (pump control)
Arduino digital pin → Relay IN2 (valve control)
Relay 1 COM → 5V, Relay 1 NO → pump positive wire
Relay 2 COM → 12V, Relay 2 NO → solenoid valve positive wire

Step 5: Wire the float switchConnect one wire to an Arduino digital pin (enable internal pull-up in code), the other wire to GND. When water is high, the switch closes the circuit.

Step 6: Connect the pump and valve

Pump negative wire → GND (5V rail)
Solenoid valve negative wire → GND (12V rail)
Position the pump at the bottom of the pool
Connect the solenoid valve to your water supply line

Step 7: Upload and testUpload the code, open Serial Monitor, and manually trigger a test cycle. Verify the pump drains fully and the valve refills to the correct level.

Setting Up the Pool

Any small container works - a bucket, a plant pot saucer, an old basin
Place it in a shaded area near where you spend time outdoors (mosquitoes prefer shade)
If you have recycled house water, use that - mosquitoes aren't picky
Keep it accessible for maintenance

Tips and Lessons Learned

Waterproof your electronics. Put the Arduino and relay in a weatherproof enclosure. The pump and float switch can get wet, everything else should stay dry.
Secure the float switch. If it shifts position, it'll read the wrong level and your cycle won't work properly.
Test the timing first. Start with a shorter cycle (every few hours) to make sure the drain/fill works before setting it to 4 days.
Don't forget to refill. If your water supply runs out or the valve fails, the pool stays empty and mosquitoes just go lay eggs somewhere else. The system only works if there's always fresh water to attract them.

Results

After about 3 weeks of running, the mosquito situation in our yard went from unbearable to barely noticeable. We can sit outside in the evening without getting eaten alive. The system runs unattended - I just check it once a week to make sure everything looks right.

Total parts cost: ~$35-40.

I used Make-it to plan this project - it generated the initial parts list, wiring, and code which I then tweaked for my setup.

Code

mosquito_trap.ino

// Mosquito Trap Automation by Make-It
// This code uses a DS3231 Real-Time Clock (RTC) to trigger a water change every 4 days.

#include <Wire.h>
#include "RTClib.h"

// Create an RTC object
RTC_DS3231 rtc;

// --- Pin Definitions ---
#define EMPTY_PUMP_PIN 7  // Digital pin connected to IN1 on the relay module
#define REFILL_PUMP_PIN 8 // Digital pin connected to IN2 on the relay module

// --- Configuration ---
const long CYCLE_INTERVAL_SECONDS = 345600; // 4 days (4 * 24 * 60 * 60 seconds)
const int EMPTY_PUMP_DURATION_MS = 60000;   // Run empty pump for 60 seconds
const int REFILL_PUMP_DURATION_MS = 60000;  // Run refill pump for 60 seconds

// We need to store the time of the last cycle. We'll use a variable for this.
// For a real-world device, this should be stored in EEPROM to survive power loss.
long lastCycleTime = 0;

void setup() {
  Serial.begin(9600);
  Wire.begin();

  pinMode(EMPTY_PUMP_PIN, OUTPUT);
  pinMode(REFILL_PUMP_PIN, OUTPUT);

  // Make sure pumps are off at startup
  digitalWrite(EMPTY_PUMP_PIN, HIGH); // Relays are often LOW-triggered, so HIGH is OFF
  digitalWrite(REFILL_PUMP_PIN, HIGH);

  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC");
    Serial.flush();
    abort();
  }

  // UNCOMMENT THE FOLLOWING LINE THE *FIRST* TIME YOU UPLOAD
  // This sets the RTC to the date and time this sketch was compiled.
  // After setting the time, comment it out and re-upload to prevent resetting the time on every reboot.
  // rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));

  Serial.println("Mosquito Trap Initialized.");
  
  // Get the current time to start our cycle timer
  DateTime now = rtc.now();
  lastCycleTime = now.unixtime();
  Serial.print("Current Unix time: ");
  Serial.println(lastCycleTime);
}

void loop() {
  // Get the current time from the RTC
  DateTime now = rtc.now();
  long currentTime = now.unixtime();

  Serial.print("Current Time: ");
  Serial.print(now.timestamp(DateTime::TIMESTAMP_FULL));
  Serial.print(", Seconds since last cycle: ");
  Serial.println(currentTime - lastCycleTime);

  // Check if 4 days (CYCLE_INTERVAL_SECONDS) have passed since the last cycle
  if (currentTime - lastCycleTime >= CYCLE_INTERVAL_SECONDS) {
    Serial.println("--- Cycle time reached! Starting water change. ---");
    runWaterChangeCycle();
    // Update the last cycle time to the current time
    lastCycleTime = currentTime;
    Serial.println("--- Water change complete. Timer reset. ---");
  } else {
    Serial.println("Not time yet. Waiting...");
  }

  // Wait for a while before checking again to conserve power.
  // For ultra-low power, you would use deep sleep modes here.
  delay(3600000); // Check once per hour (3600 * 1000 ms)
}

void runWaterChangeCycle() {
  // Step 1: Turn on the emptying pump
  Serial.println("Starting empty pump...");
  digitalWrite(EMPTY_PUMP_PIN, LOW); // LOW turns the relay ON
  delay(EMPTY_PUMP_DURATION_MS);

  // Step 2: Turn off the emptying pump
  digitalWrite(EMPTY_PUMP_PIN, HIGH); // HIGH turns the relay OFF
  Serial.println("Empty pump finished.");
  delay(5000); // Wait 5 seconds before refilling

  // Step 3: Turn on the refilling pump
  Serial.println("Starting refill pump...");
  digitalWrite(REFILL_PUMP_PIN, LOW); // LOW turns the relay ON
  delay(REFILL_PUMP_DURATION_MS);

  // Step 4: Turn off the refilling pump
  digitalWrite(REFILL_PUMP_PIN, HIGH); // HIGH turns the relay OFF
  Serial.println("Refill pump finished.");
}

Credits

Gal Ofel

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Eco-Friendly Automated Mosquito Trap - Arduino Nano

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

The Problem

How It Works

Circuit Overview

Step-by-Step Assembly

Setting Up the Pool

Tips and Lessons Learned

Results

Schematics

Wire Diagram

Code

mosquito_trap.ino

Credits

Gal Ofel

Comments

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Eco-Friendly Automated Mosquito Trap - Arduino Nano

Eco-Friendly Automated Mosquito Trap - Arduino Nano

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

The Problem

How It Works

Circuit Overview

Step-by-Step Assembly

Setting Up the Pool

Tips and Lessons Learned

Results

Schematics

Wire Diagram

Code

mosquito_trap.ino

Credits

Gal Ofel

Comments

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