What a thermal camera shows about a bee hive in a Miami wall

Why a colony glows on the screen

Worker bees keep the brood area close to 93 F (34 C) around the clock, warming it by shivering their flight muscles and cooling it by fanning and spreading water. Research on colony heating puts the working range at roughly 32 to 36 C, and developing brood is harmed when it drifts far outside that band.

That tight control is what a camera picks up. Few other things inside a wall cavity hold one temperature all day and all night. The bright shape you see is the nursery, where eggs, larvae and capped pupae sit. Honey stores usually sit above and to the sides of it and read cooler, closer to the wall itself. So when a scan shows a warm oval the size of a dinner plate, plan on comb reaching beyond that outline, sometimes well beyond it. The opening in a wall removal is laid out with that margin in mind.

The camera reads the skin of the wall

Most thermal imagers work in long-wave infrared and measure only the surface they are pointed at. They do not look through drywall, stucco, glass or tile. What they record is heat that has already traveled through the material to the face you are standing in front of.

Half-inch drywall over a stud bay passes that heat quickly, so a colony behind it tends to show as a fairly crisp bloom. Concrete block finished in stucco is a different story. Block has hollow cores, and some of those cores are filled with concrete and steel bar for strength. Filled cores, hollow cores and mortar joints each carry heat differently, so a block wall can show a faint grid of warm and cool stripes even with no bees in it. A colony tucked into a hollow core warms the face only slightly and spreads that warmth over a wider area. Shiny surfaces add one more trap: polished metal, and to a lesser degree glass, reflects heat from elsewhere in the room, so the reading on it says little about what sits behind.

Miami sun is the loudest signal in the picture

Summer highs here run from the mid 80s to the mid 90s F (29 to 35 C). That overlaps the band the bees are holding inside the nest. On a south or west wall in the afternoon, the stucco can climb past brood temperature, and the hive either disappears into the glare or shows up as a cooler spot inside a hot wall.

Timing fixes most of this. A scan before sunrise, after dark, or on a heavy overcast day lets the wall settle while the bees keep their nursery steady. The inside face of an outside wall is often the clearest view of all, because an air-conditioned room gives the camera a cool background to read against.

During the rainy season, which runs from mid-May to mid-October, wet stucco cools as it dries. That leaves blotchy cool areas that can hide a weak warm patch, so a scan right after a storm is worth repeating once the wall has dried.

Heat sources that imitate a hive

Plenty of warm things live inside walls and ceilings, and each one leaves its own kind of mark:

• Hot water lines show as long, narrow streaks that follow a pipe run.
• A water heater closet or a refrigerator against the other side warms a broad, square area.
• Recessed lights and bath fans make round hot rings in a ceiling.
• Electrical panels and dimmers glow at the box and along the wire.
• A rodent nest is warm too, though it rarely holds a steady temperature.
• Damp insulation or a leak usually reads cooler, not warmer.

A hive tends to be an irregular, rounded patch that stays put from morning to night. Before anyone cuts, that reading gets cross-checked against what the bees are doing outside: where they enter, whether foragers return with pollen on their legs, and whether a low hum comes through the wall when you press an ear to it.

A small entrance tells you little about the comb

Bees will use almost any gap they can squeeze through: a crack along a stucco seam, the space around a hose bib or conduit, a missing piece of soffit screen, a loose roof tile. The hole you can see is only the front door. Inside, the colony builds wherever the cavity has room, which might be two feet up the wall, sideways along a block course, or across a stud bay.

This is where the camera earns its keep. Cutting at the entrance and hunting for comb leaves a larger and messier repair than opening the wall right over the nursery. On soffit and eave jobs and tile roof colonies, a scan from the attic or the room below can show which direction the comb runs before a single tile comes off. Plugging that small opening yourself is the wrong move, since the bees inside will look for another way out, and that way can lead into the house.

What the screen will never tell you

Some colonies give off almost no useful heat. A swarm that moved in a few days ago has built little comb or brood, and its small cluster may show as a faint patch or not at all. A colony that died or left is cold, yet its comb and honey are still in the wall, where honey can soften and seep in summer heat and draw ants, roaches and new scout bees. That is why comb and honey cleanup matters even when a scan comes back quiet, and why old comb is one reason a cleared wall can attract a fresh colony.

The camera also cannot tell honey bees from a wasp nest, measure how much honey is stored, or say whether the comb is stuck to wiring. Those answers come from looking, listening and, in the end, from opening the wall.

Older stone and tile buildings

In Coral Gables, the original plan called for Mediterranean Revival design, and the city takes its name from a family house built of Miami limestone, the local rock often called coral rock, under coral-colored tile. Thick stone holds and spreads heat slowly, which softens the bloom a nursery would make, so these scans favor cool hours and interior views.

In Miami Beach, the Architectural District holds what is described as the world's largest collection of Art Deco buildings, most of them built between the Depression and the early 1940s. On a historic facade, a condo board will want the opening kept as small and as well placed as possible, and a good scan is how that gets planned. Owners of older homes elsewhere in Miami face the same trade-off between finding the comb and protecting original finishes.

From the scan to a sealed wall

Once the nursery is mapped, the colony comes out alive and goes to a beekeeper. Nothing is poisoned. The wax and stored honey the scan pointed to come out along with the bees, the cavity gets wiped down, and their old doorway is closed off. Patching the stucco, drywall or tile falls to our own licensed trades, a crew of contractors, roofers and painters, so you are not left hiring someone else to match the finish. Should a new colony move into a place we closed up, we come back out under the workmanship warranty.

The quote is free. Height and access set most of the price: about $300 to $400 when the nest can be reached from the ground, and into the thousands once it sits up in a wall or under tile and needs repairs after removal. The cost page walks through what moves that number. If your insurer or your board needs a paper trail, just ask, and the job photos come with a line-by-line invoice.

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