Spider Webs in Your Grill Burner Tubes? Here's What to Do

The grill sat closed for a few weeks. Maybe a month or two. You fire it up for the first cook of the season and something’s wrong — yellow flames instead of blue, weak heat, or worse, a whoosh sound coming from inside the burner box. Welcome to the most common spring grilling problem in America: spider webs in your venturi tubes.

This is fixable in 15 minutes. Once you know to look for it, you’ll never be surprised by it again.

Why spiders nest in burner tubes

Propane has an additive called mercaptan — a chemical that makes natural-leaking propane smell detectable. Mercaptan smells like sulfur, eggs, or skunk depending on the formulation, and it has a similar molecular profile to compounds that attract certain spiders (especially the Western black widow and various small wasps).

The venturi tubes — the metal tubes that connect each burner to the gas inlet — are dark, narrow, and slightly redolent of mercaptan. To a spider, that’s prime nesting territory. They build webs across the tube opening, and within a few weeks, the airflow into the burner is partially or fully blocked.

The infestation is most common:

• In spring, after a winter of cooker disuse
• After 2-4 weeks of any non-use period during warm seasons
• In humid climates where spider activity is highest
• On grills stored uncovered or with covers that don’t fully seal at the burner box

How to identify the problem

Symptoms that point to webs in the venturi tubes:

• Yellow flames instead of blue, especially on one or two specific burners
• Burner won’t ignite even with a good igniter spark
• Significantly weaker heat than expected, even on high
• Whooshing or popping sounds during ignition
• Flame instability — the flame flickers between zones or dances irregularly
• Most diagnostic: the symptom appeared after the grill sat unused for several weeks

If you’ve recently used the grill regularly with no issues, spider webs are unlikely. If you’re firing up after spring storage, they’re the first thing to check.

Finding and clearing the webs

This is the procedure. It’s straightforward but mandatory before continuing to cook.

1. Shut off the propane at the tank and disconnect the regulator. Non-negotiable safety step. Don’t skip.

2. Remove the cooking grates and flame tamers/heat shields. Set them aside. Photo the layout if needed.

3. Locate the burner mounting hardware. Most grills have one screw, pin, or clip securing each burner to the rear of the firebox. Look for a small fastener at the back of each burner.

4. Remove the burners. Lift each burner up and away. The burner slides off the venturi tube, exposing the gas valve opening.

5. Inspect with a flashlight. Look down the venturi tube from the burner end. You’re looking for: white or grey webbing, dirt, dead insects, dust accumulation. A blocked tube has visible material at the opening or in the throat.

6. Clear with a venturi brush, pipe cleaner, or coat hanger. Push the cleaning tool through the entire length of the tube, turning gently as you go. Pull it back, push again — multiple passes. Inspect again afterward.

7. Reassemble in reverse order. Burners on, secure with the original fastener, flame tamers, grates.

8. Reconnect propane SLOWLY. Open the tank valve gradually — count to 10 as you open. This prevents tripping the regulator’s safety lockout.

9. Light the grill carefully. Stand to the side, not over the grill. Light each burner one at a time. Watch for blue flames. If you still see yellow on a burner, it may need a second pass with the cleaning tool — or the venturi tube may not be fully clear yet.

Prevention — how to keep them out

The infestation is preventable with a couple of habits:

Cover the grill tightly when not in use. Especially during spring and any extended off-period. The cover doesn’t need to be expensive, but it does need to fit and seal at the burner area.

Run the grill at high heat for 10 minutes before the first cook of any new season. Even if you ran it last week, 10 minutes of high heat any time the grill has sat unused for a couple weeks burns out small intrusions before they become full webs.

Inspect every spring. Even if the grill seems to be working fine. A 5-minute check confirms there’s no developing problem and makes you faster at the procedure for when you do find webs.

For grills in extreme spider territory, some brands sell venturi tube screens — small mesh covers that fit over the air-intake openings and physically block insect entry while still allowing airflow. Universal screens fit most grills; brand-specific ones fit better.

Brand-specific notes

Weber Genesis / Spirit: burner removal is straightforward. Look for the rear pin or screw. Reinstall pays attention to alignment with the gas valve.

Char-Broil: TRU-Infrared models have different burner geometry — the venturi tube is integrated into a flat infrared emitter. Cleaning is similar but the tubes are shorter.

Napoleon: burners often have rear cotter pins. Don’t lose them — they’re easy to replace if needed.

Big Green Egg / kamados: no venturi tubes. They run on charcoal, not gas. This article doesn’t apply.

Kamado Joe (gas-assist models, rare): the gas-assist starter has a tiny venturi-like opening that can clog. Different procedure — refer to your model’s manual.

Frequently asked questions

How do I know if it's spider webs vs. something else? +

If the symptom appeared after the grill sat unused for several weeks, and you can see white or grey material in the venturi tube with a flashlight, it's webs. If the symptoms appeared during continuous use, it's likely something else (regulator, burner damage, fuel issue) — see the [yellow flame guide](/grill-care/yellow-flame-on-gas-grill-causes-and-fixes) for the broader differential.

Are there really spiders in there or is this just an old wives' tale? +

Real. The CDC, multiple gas grill manufacturers, and propane safety boards have all documented this — it's specifically a behavior of certain spiders attracted to mercaptan. Western black widow and yellow sac spiders are the most-frequently identified culprits in published incident reports.

Can I just burn the webs out by lighting the grill? +

Sometimes the webs do burn out on first ignition. But if the blockage is significant, the grill may produce a flashback (mini-explosion inside the burner) instead. The 15-minute manual inspection is much safer than rolling the dice on burn-through.

What's a venturi brush and where do I get one? +

A venturi brush is a long, narrow brush specifically sized for cleaning gas grill venturi tubes. Hardware stores and grill-supply shops carry them; they're $5-15. A bent coat hanger also works, as does a thick pipe cleaner. The exact tool matters less than getting the bristles or wire fully through the tube length.

How often does this need to be checked? +

Once a year minimum, at the start of grilling season. Plus any time the grill has been unused for 4+ weeks during warm months. A quick visual through the burner ports often catches obvious blockages without removing the burners — but the full inspection is worth doing annually anyway.

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