Surviving the UK Heatwave: How to Keep Your Jumping Spiders (and Their Livefood) Alive
UK houses are built like greenhouses. When a heatwave hits, our indoor spaces quickly turn into ovens.
If you've struggled to keep your bugs alive this week, you are not alone. Just a few days ago, we lost our entire current stock of live greenbottle flies to the sudden spike in temperature. It was a stark reminder of just how fragile these micro-ecosystems are when the thermometer climbs.
To help you avoid the same heartbreak and frustration, we've put together a quick survival guide to keeping both your eight-legged friends and their dinner hydrated and healthy until the weather breaks.
Part 1: Keeping Your Jumping Spiders Hydrated Safely
Most established jumping spiders handle warmth quite well, but stagnant, hot air and sudden dehydration will kill them quickly. Here is how to keep them safe without creating a hazard:
The Cotton Wool Trick: Since open water dishes pose a major drowning risk due to surface tension, skip them entirely. Instead, place a wet cotton wool ball into a tiny bottle cap or small dish. It holds a massive amount of water, won't dry out in an hour, and gives your spider a perfectly safe spot to drink from without any risk of getting stuck. Just make sure the cotton wool isn't soaked as a fully saturated cotton ball can also pose a drowning risk!
Fine Mist Only: Continue to use a fine mister to spray a few light droplets onto the side of the enclosure once or twice a day. They will happily drink directly off the acrylic or plastic safely.
Prioritise Cross-Ventilation: Humidity combined with stagnant heat creates a deadly, bacteria-ridden sauna. Make sure your enclosures have excellent cross-ventilation (airflow moving through the sides, not just venting out the top) to keep the air fresh and moving.
Relocate Down Low: Heat rises. If your display shelves are high up or near a window, temporarily move your enclosures down to a lower shelf, or into the coolest, most shaded room in the house.
Part 2: The Greenbottle Challenge (Ditch the Plastic Tubs!)
Livefood is often the first thing to crash in a heatwave. Greenbottle flies have incredibly fast metabolisms that accelerate even further in the heat, causing them to rapidly burn through their energy and dehydrate.
Switch to a Net Enclosure: Keeping your hatched flies in the standard plastic retail tubs they arrive in is a major risk right now. The flies breathe faster in the heat, creating rapid condensation inside the plastic. If their wings touch those wet walls, they get stuck and die. Moving your flies into a mesh net enclosure ensures maximum airflow and zero condensation.
The Fly Fix (Sugar and Moisture): Once greenbottle pupae hatch into flies, they need immediate access to moisture and carbohydrates. A small piece of reptile jelly/jelly pot or a cotton wool ball soaked in sugar water gives them the energy they need to thrive.
No Kitchen Sponges: Avoid standard kitchen sponges for your flies' water; they harbour deadly bacteria within hours in high temperatures. Instead, those same cotton wool balls or cosmetic pads you use for your spiders work perfectly here too! Soak them in fresh water or sugar water to give your flies a clean, safe drink. You can also use bug gel, wet paper towels (changed daily), or fresh slices of carrot and potato for extra moisture.
Summary Checklist: Quick Swaps for the Heatwave
| Keep Item | Normal Care | Heatwave Adjustment |
|---|---|---|
| Jumping Spiders | Regular light misting | Move to floor level; provide a soaked cotton wool ball for safe drinking; prioritise cross-ventilation. |
| Greenbottle Flies | Kept in plastic shipping tubs | Move entirely into a mesh net enclosure; provide a sugar-water cotton ball/pad or jelly pot; keep in a cool room. |
| Other Feeders (Curly wings, Roaches) | Standard enclosure spots | Add fresh carrot or potato slices daily for safe moisture; move to the coolest room in the house. |
Don't let a sudden spike in British weather catch you off guard. Check your setups twice a day, keep the air moving, and look after your feeders—because healthy livefood means a healthy spider.
How are your setups holding up in this weather? Let us know, or drop us a message if you need any emergency troubleshooting advice!
Frequently Asked Questions: Heatwave Spider Care
What temperature is too hot for a jumping spider?
Jumping spiders can tolerate warmth well, but sustained temperatures above 30°C — particularly combined with stagnant air and low humidity — become dangerous. The real killer isn't heat alone; it's heat combined with dehydration and poor ventilation. During a UK heatwave, prioritise airflow and hydration over temperature alone.
Can jumping spiders die from a heatwave?
Yes. Dehydration and overheating are both genuine risks during a UK heatwave, especially in south-facing rooms or high shelves near windows. The most vulnerable setups are those with poor cross-ventilation and no safe water source. Act quickly: move enclosures to a cooler, lower position and provide a damp cotton wool ball for drinking.
How do I give my jumping spider water safely during a heatwave?
Never use open water dishes — jumping spiders can drown due to surface tension. The safest methods are: a damp cotton wool ball in a bottle cap (not soaked, just moist), or fine misting of the enclosure walls once or twice a day so your spider can drink droplets directly off the surface.
Why are my greenbottle flies dying in the heat?
Greenbottle flies have fast metabolisms that accelerate further in high temperatures, causing rapid dehydration and energy depletion. The main culprit is usually condensation inside plastic tubs — flies breathe faster in the heat, the moisture builds up on the walls, and their wings get stuck. Switch to a mesh net enclosure immediately for maximum airflow, and provide a sugar-water cotton ball or jelly pot for energy.
Should I turn off my heat mat during a heatwave?
Yes — if your ambient room temperature is already reaching 26°C or above, switch off your heat mat entirely. Your thermostat should handle this automatically if it's set correctly, but it's worth double-checking. During a heatwave, the priority shifts from heating to cooling and ventilation.
Where should I move my spider enclosures during a heatwave?
Move enclosures down low — heat rises, so floor level or low shelving is significantly cooler than high display shelves. Choose the most shaded, north-facing room in the house if possible. Avoid anywhere near windows, radiators, or south-facing walls.