Varroa Mite Management & Hive Health

What Are Varroa Mites?

• Scientific name: Varroa destructor
• Origins: Jumped from Apis cerana to Apis mellifera in the 20th century
• Physical description: Rust-colored, flat, oval parasites ~1.1 mm in size
• Where they live: Inside brood cells and on adult bees (prefer drones)
• Why they’re deadly: Feed on bee fat bodies (not hemolymph), weakening bees and spreading viruses

Varroa mites are external parasites that feed on the fat body tissue of honey bees, not just their hemolymph (as once believed). They transmit multiple viruses (like DWV and ABPV) and suppress bee immunity, often leading to colony collapse.

Detection & Monitoring Methods

1. Alcohol Wash (Gold Standard)

• Kills ~300 bees from brood frame, shakes them in alcohol to dislodge mites
• Accurate; measures mite load as mites per 100 bees
• Used by researchers and commercial operations

2. Sugar Roll Test

• Non-lethal alternative using powdered sugar
• Less accurate if humidity is high or if technique is off

3. Sticky Boards

• Place beneath screened bottom boards
• Passive method; best used in combination with active tests

4. Smart Hive Monitoring (New for 2025)

• IoT-based hives now include mites per day sensors, CO₂ and brood detection
• Early warning systems linked to mobile apps

How to treat Varroa Mite naturally?

1] Early Detection and Monitoring Techniques

• Use of sticky boards, alcohol washes, sugar rolls
• Smart hive sensors and IoT tools for mite tracking
• Visual signs of infestation and mite load thresholds.

2. Natural and Non-Chemical Control Methods

• Essential oils (thymol, oregano, eucalyptus)
• Drone brood removal and brood interruption techniques
• Powdered sugar dusting and screened bottom boards.

3. Chemical Treatment Options

• Oxalic acid vaporization (safety and timing)
• Formic acid pads (MAQS)
• Amitraz (Apivar) and resistance concerns

4. Integrated Pest Management (IPM) Strategies

• Combining multiple approaches over the beekeeping season
• Rotating treatments to avoid resistance
• Timing interventions with the brood cycle

5. Colony Health and Immunity Support

• Nutrition: pollen substitutes and diverse forage
• Hive ventilation and moisture control
• Queen health and genetic resistance to mites

Visible Signs of Varroa Infestation

1. Deformed Wing Virus (DWV)

• Bees emerge with crumpled, stubby, or missing wings
• Caused by viruses amplified by Varroa feeding
• Often seen on nurse bees and newly emerged workers

2. Spotty Brood Pattern

• Brood comb has scattered empty cells or irregular capping
• Nurse bees are removing infected larvae (a good but alarming sign)
• May also indicate hygienic behavior or severe virus infection

3. Dead or Dying Brood

• Mummified or partially developed bees found in cells
• Signs of Paralysis Virus, DWV, or high Varroa stress
• May resemble chalkbrood but found in colonies with high mite counts

4. Shiny or Greasy Bees

• Bees appear oily or slick due to mite damage
• Often go unnoticed but visible under strong lighting

Behavioral Signs

5. Crawling Bees at Hive Entrance

• Bees walking rather than flying, often wingless or shaky
• Sign of nerve damage from DWV or mite pressure

6. Increased Aggression or Irritability

• Bees are more defensive, especially near brood frames
• Likely due to stress or mite-damaged nurse bees

7. Reduced Foraging or Bee Population Drop

• Sudden drop in worker numbers during peak season
• Indicates mite-induced weakening or shortened bee lifespan

Diagnostic Signs (What to Look for in the Hive)

8. Visible Mites on Adult Bees

• Mites appear as reddish-brown spots on thorax or between abdominal segments
• Most mites stay hidden in the brood cells, so seeing them on adults means very high infestation

9. White Mite Droppings

• White spots (uric acid) in capped brood cells
• Look at the walls of opened drone brood for droppings

Life Cycle of Varroa Mites

The Varroa mite has a biphasic life cycle, meaning it has two main phases:

• A phoretic phase on adult bees
• A reproductive phase inside capped brood cells

1. Phoretic Phase (On Adult Bees)

• Duration: 4 to 14+ days (can extend during broodless periods)
• Role: Transportation and feeding
• Where: Mite clings to adult bees (mainly nurse bees) and feeds on their fat body tissue, not blood as once thought
• Impact: Transmits viruses like Deformed Wing Virus (DWV) and suppresses bee immunity
• Key behavior: Female mites use this phase to locate suitable brood cells for reproduction

2. Reproductive Phase (Inside Capped Brood Cells)

• Entry: Female mite enters a larval brood cell (usually drone or worker) just before capping (12–24 hours prior)
• Timing: Depends on the development time of the bee:
  • Worker brood: 21 days
  • Drone brood: 24 days
• Why drone brood? Mites prefer drones due to their longer development, allowing more mite offspring to mature

Reproduction Timeline Inside the Cell:

3. Emergence & Repeat

• Once the bee emerges, the mother and mated daughter mites exit with it
• They enter the phoretic phase again and seek new brood cells
• The cycle repeats approximately every 2–3 weeks