Bed Bugs in Calgary: How Long They Survive and Why Climate Matters

Did You Know Bed Bugs Can Survive Longer Than You Think?

A Calgary-focused look at how temperature, humidity, and biology shape bed bug resilience.

Did you know that bed bugs living in a typical Calgary home or apartment can survive far longer without feeding than the “three-month rule” you often see online?

It’s a “fact” that gets repeated so often that people stop questioning where it came from. Someone heard it from a manager. Someone read it in a Google snippet. Someone decided that because Calgary is cold and dry, bed bugs must die faster here than in humid places. And suddenly: “Three months. That’s how long they live without food.”

As with most things in pest control, the truth is more interesting, and more complicated.

Not a Myth, But Not the Full Story: The Truth Behind the “Three-Month Rule”

Let’s start here:
Yes, bed bugs can die after a few months without feeding.
But no, that isn’t a universal timeline.

Cimex lectularius, the most common bed bug species we deal with in Calgary, is highly adaptable. Longevity without food depends on a few key variables:

1. Temperature

• Warm conditions speed up metabolism, meaning bed bugs burn through their reserves faster.

• Cool conditions slow everything down, letting them conserve energy longer.

This matters, because many people assume our cold winters make bed bugs short-lived. But indoors? Calgary homes, condos, and apartment buildings are consistently warm year-round. And in multi-unit buildings, they are often warmer than single-family houses.

Warmth means activity.
Warmth means faster reproduction.
Warmth means a bed bug can thrive for months, often well beyond the expected three-month window.

2. Humidity

Calgary is famous for its dry climate, but “dry outside” and “dry inside” are not the same thing.

• Many Calgary buildings maintain surprisingly high humidity levels, especially older apartments and units with large numbers of occupants.

• Higher humidity slows dehydration, which helps bed bugs survive longer.

When you combine the right temperature and humidity, the theoretical starvation window stretches significantly.

3. Life Stage

Nymphs (juveniles) generally can’t survive as long as adults.
Adults, especially fed adult females, can hold out the longest.

So, a vacant suite might have a few survivors even after months of inactivity, depending on development stages and hatching schedules.

The takeaway:
The “three-month rule” is a convenient guideline, but not a dependable one, especially in Calgary’s indoor climate.

Why Bed Bugs Can Survive Months Without a Meal

Bed bugs are built for intermittent feeding. In nature, their original hosts were bats and birds, which didn’t always stay put. To survive, bed bugs evolved a slow, flexible metabolism that lets them coast through long stretches of food scarcity.

When food sources disappear, bed bugs don’t panic.
They don’t waste energy.
They simply wait.

Their development slows.
Movement decreases.
Reproduction pauses.

A bed bug that would normally be active every week or so may go dormant for long intervals until a new host appears.

This waiting game is one reason infestations can feel unpredictable. It’s also why many professional bed bug treatments aren’t as effective in vacant units. Bed bugs will usually sit out their dormant period in a well hidden spot. Applied pesticides rarely reach these deeply hidden areas of a structure. Bed bugs in this dormant state, will only emerge when they sense a food source nearby, or when they become so dehydrated that they must feed or risk death. By the time these dormant bugs emerge from hiding, there is often little to no active pesticide remaining; and even if there is, it won’t kill instantly, and won’t prevent new occupants from receiving at least one round of bites before the bugs begin to die. A unit can be empty for months, and the moment a new person moves in, they suddenly have activity. The bugs didn’t magically appear, they were simply conserving energy.

But here’s an important detail most people never hear:

They Can Survive Without Feeding… But They Can’t Grow

One of the most useful pieces of bed bug biology to understand is this:

Bed bugs must feed to molt. Growth stops without blood.

Bed bugs go through five nymphal stages (instars) before reaching adulthood.
Each stage requires a blood meal to progress.

That means:

• They can wait for months without eating.

• But they cannot develop until a host becomes available.

• The population only grows when feeding is happening.

Why does this matter?

Because a long-term, low-activity infestation in a vacant unit can sit in stasis. The moment people return—new tenants, contractors, family members—the bugs start feeding and development resumes.

When Humans Aren’t Around, Bed Bugs Don’t Necessarily Die Off

A lesser-known, but very real survival strategy:
Bed bugs are perfectly capable of feeding on other animals when humans aren’t available.

What other hosts can they use?

Cimex lectularius (common bed bug) are generalist feeders requiring blood from mammals or birds, and have been known to feed on a wide variety of blood sources. In and around the Calgary area, we have identified C. lectularius feeding on:

• Swallows [We’ve identified C. lectularius (common bed bug) in abandoned swallow nests where Oeciacus vicarius (Swallow bug), or even possibly cimex adjunctus (Eastern Bat Bug) was expected]

• Pigeons [Identified C. lectularius living in several pigeon nests on Calgary apartment balconies where cimex columbarius (pigeon bug) was expected]

• Bats [usually C. adjunctus (Eastern Bat Bug) in Alberta, but C. lectularius (common bed bug) can feed on bats as well]

• Chickens [on rural properties and farms]

• Other small mammals, including pets [in rare or desperate situations]

Humans are their preferred host because our skin is thinner, we sleep predictably, and we lack feathers or thick fur. But preference doesn’t equal dependency.

This is important for a few reasons:

Vacant apartments aren’t always safe.

A vacant unit with a pigeon nest in a nearby exterior vent or on a balcony can sustain a small bed bug population.

Infestations in unusual places may have animal sources.

Finding bed bugs in:

• garages

• sheds

• basements

• mechanical rooms
  …sometimes hints at a nearby wildlife host, not a human one.

Pets rarely sustain full infestations—but they’re not impossible feeders.

Dogs and cats typically only get bitten incidentally. Their fur makes feeding difficult, and pets are more likely to spread bed bugs around homes because their fur can often catch and drag bed bugs to new areas. But in extreme starvation scenarios, bed bugs will take what they can get.

Seasonal Reminder: Calgary’s Winter Cold Doesn’t Kill Bed Bugs

Every winter, people ask whether they can put furniture or bagged items outside to freeze bed bugs.

The short answer:
Sometimes. But usually not.

The longer, more accurate answer:

Cold affects bed bugs, but not the way people assume.

• Bed bugs die quickly only at temperatures around –30°C or colder, and even then, exposure needs to be prolonged and consistent.

• Around –20°C, they can survive for days or longer depending on wind, insulation, and hiding spots.

• If an item is insulated, even slightly, cold won’t penetrate fast enough to kill them.

Calgary absolutely gets these temperatures…
But consistency is the problem.

Items left outside:

• warm in the sun

• have insulated pockets

• may not reach lethal internal temperatures

• may not stay cold long enough

• may allow bugs to simply hide deeper

And of course, indoor bed bugs never experience these temperatures at all.

What cold does cause:

• Slowed activity

• Delayed reproduction

• Dormancy until temperatures increase

• Migration toward heat sources (walls, vents, window/door frames, outlets )

So, while winter weather might reduce spread in detached homes, it does nothing to solve an established indoor infestation.

As a rule of thumb:

If your furnace keeps you comfortable, it keeps bed bugs comfortable too.

Key Takeaways

• The standard “three-month starvation rule” is a rough guideline, not a predictable timeline.

• Calgary’s warm, humid indoor environments allow bed bugs to survive far longer than most people think.

• Bed bugs pause their development when unfed. They don’t decline quickly.

• They can feed on birds, and occasionally pets when humans aren’t around.

• Cold weather does not reliably kill bed bugs unless it is extremely cold for an extended period, with open exposure.

• Indoor heating in winter gives bed bugs everything they need to survive.

• If you suspect bed bug activity, early identification and professional assessment are always the safest option.

Final Thoughts

Bed bugs are adaptable survivors, shaped by millions of years of evolution. But with good information, and the right strategies, they’re absolutely manageable. Understanding their biology is one of the strongest tools we have for designing effective, modern treatment plans tailored to Calgary’s climate and housing conditions.

If you have questions about your home, a suspected infestation, or unexplained bites, we’re always here to help.