The Curious Case: Why Do Bees Sting Watermelons?

Why Do Bees Sting Watermelons?

Nothing signals summertime quite like slicing into a juicy watermelon on a hot day. But sometimes when you cut into a watermelon, you find an unwelcome surprise – angry bees pouring out from the interior! This bizarre phenomenon arises from the unique lifecycle and behaviors of one specialist bee species. Keep reading to learn all about why bees set up their hives inside watermelons and what causes them to aggressively sting the flesh.

bees landing on a red beehive

The Culprit Behind Watermelon Stings

The bees that colonize watermelons belong to the species Tetraloniella nana, commonly known as the watermelon bee. Watermelon bees range across the southern United States, specializing in gathering pollen from plants in the Cucurbitaceae family, which includes watermelons, squash, pumpkins, cucumbers, and gourds.

The watermelon bee is on the small side, measuring only 5 to 7 millimeters long. They have a dark brown hue with light gray stripes on the abdomen. Males and females look similar except males have longer antennae.

Watermelon bees construct intricate tunnels and chambers inside thick-rinded melons, pumpkins, and gourds to house their nests. A single nest may contain up to 1000-2000 watermelon bees! The moist, nourishing flesh of the melons provides the perfect protected environment for them to rear their young.

Why Watermelons Make Ideal Bee Homes

Watermelons have several beneficial characteristics that make them attractive egg-laying and nesting sites for the bees:

  • Thick, durable rinds provide protection from predators and the elements.
  • Abundant tender fruit flesh supplies nutrients.
  • The hollow cavities allow enough space for large nests.
  • The buoyancy of the melons keeps nests safe from flooding.
  • Water content provides adequate moisture.
  • Warmth from sun exposure helps incubate pupae.
  • Melons contain chemicals that deter mold growth.

Watermelon bees specifically seek out older, over-ripened melons that have very soft rinds. The female bees test multiple melons by drilling trial entry holes. Once an ideal melon is found, they tunnel extensive networks inside the rind. These become nursery chambers.

bees making honey in a beehive

How Watermelon Bee Nests Develop

After making entrance holes, the female bees excavate winding tunnels that open up into larger rounded brood cells within the melon. The brood cells are carefully constructed from the melon’s own flesh and juices which harden into a cellulose-like substance.

In each cell, an egg is laid upon a mixture of pollen and regurgitated nectar for food. The egg hatches within a few days into a larva. Larvae develop for around three weeks, feeding on the stored pollen and maturing into pupae.

Adult bees eventually emerge from the pupal stage after metamorphosis is complete, roughly a month from when the eggs were first laid. They chew through the cell caps and tunnel their way out to leave the melon. After mating, new females resume the cycle, using old nests or creating new ones in fresh melons.

Why Bees Aggressively Sting When Disturbed

As bees develop brood cells and stockpile pollen inside melons, they become extremely defensive of their nests. When melons containing mature bee colonies are jostled, cut into, or crushed, the bees perceive it as an attack on their home and offspring.

The bees swarm out in an aggressive attempt to sting and repel any intruders. Their stingers inject a painful venom as a defense strategy. Stinging also releases pheromones that call other colony members to join in attacking the threat.

Even harmless actions like picking up or accidentally dropping a melon can trigger mass stinging if bees have already colonized the interior. The bees have invested so much energy establishing their colonies that they mount intense defenses to protect their investment.

Stinging anyone tampering with an occupied melon helps deter future disturbances. The behavior evolved because it enhanced colony survival. But it creates a nasty interaction when humans unknowingly cut into a bee-filled melon!

bees in a glass beehive

Signs a Watermelon Contains a Bee Colony

Watermelon bees tend to nest in melons left unharvested in fields, not store-bought ones. But occasionally bees do infiltrate commercial crops. Watch for these signs a watermelon may have an active bee nest inside:

  • Tiny (1-2 mm) entrance holes chewed into the rind. Many holes clustered together.
  • A soft hollow sound when thumping the side of a melon, versus a dense thud.
  • Leaky juice dripping from tiny holes in the rind.
  • Wilting stem as bees consume nutrients and moisture.
  • Increased weight due to bees, pollen, and wax inside.
  • Rind surface dried out from bees gathering fibers to build nest structures.

Tapping and closely inspecting melons can help detect telltale signs before cutting them open. Prodded bees may briefly emerge and buzz around exit holes. Odd holes, leaks, or hollow sounds signal it’s safest to discard the melon.

Preventing Encounters With Watermelon Bees

To avoid unwanted melon bee stings, look for signs of nesting and contamination in the rind before slicing. Also:

  • Pick watermelons promptly once ripe to prevent bee colonization.
  • Harvest melons away from known bee nesting areas.
  • Seal any small holes in melons with tape to block entry.
  • Keep inspecting melons while carving to stop at the first sight of bees.
  • Wear protective clothing just in case when harvesting and cleaving melons.
  • Remove and destroy melons showing evidence of bee activity.
  • Quickly refrigerate cut melons to immobilize any bees inside.

With caution and proper precautions, watermelon lovers can continue enjoying their favorite fruit while avoiding painful stings. Melon farmers should scout crops for bee homesteads and selectively remove infested fruits to prevent hive buildup. Awareness and diligent inspections are key to preventing unwelcome bee surprises at your next picnic or barbecue.

a lot of bees landing on a beehive

The Perspective of the Bees

While being stung inside a watermelon certainly ruins the experience for any hungry humans, it’s important to remember the bees are just being loyal guardians. The melon provides the perfect sanctuary for them to pass their genes on to the next generation. Their fierce stinging is simply an instinctive defense of their offspring.

Watermelon bees play an important role as specialist pollinators of vital food crops. Without them, many melons and gourds would fail to be adequately pollinated. The bees are just looking for a safe home, even if their choice of real estate seems bizarre and painful to us.

Finding an inadvertent bee colony when carving into a watermelon can quickly turn a relaxing summer day into chaos. But if we remain calm and careful around these misunderstood insects, there’s room for all to enjoy the sunny season. With understanding and proper precautions, we can appreciate both juicy watermelons and the bees that pollinate them.


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