Best budget basking bulb for Argentine tegu

Getting heating and UV lighting right is the single most important factor in reptile health — the majority of common reptile illnesses, from metabolic bone disease to respiratory infections, trace back to incorrect temperatures or inadequate UV. Argentine black and white tegus are a great example of a species that really suffers when basking temps fall short — they need a serious hot spot to digest properly and stay active. To point you toward the best value setup, can you tell me how old your tegu is, what size enclosure you're working with, and what heating equipment you've currently got in place?

That's the classic problem with standard incandescent bulbs — they spread heat too diffusely to build a proper tegu basking spot. You need that hotspot hitting 50–55°C for a juvenile tegu so they can thermoregulate and digest efficiently. The good news is you don't need expensive kit to get there. What height is your basking fixture sitting above the basking surface?

Perfect, that's a workable distance. My recommendation is the Arcadia Halogen Heat Lamp — specifically the 75W or 100W version depending on your fixture. Halogen bulbs concentrate heat into a tighter beam than standard incandescents, which is exactly what you need to push that basking spot up to tegu-appropriate temperatures without having to go to a much higher wattage. They're also significantly cheaper to run and last longer than traditional bulbs. At 30cm mount height, the 75W will likely get you to 48–52°C and the 100W should comfortably hit 52–56°C — so I'd suggest the 100W to give yourself headroom, especially as he grows and the enclosure gets upgraded. You'll find it on Amazon UK for around £8–10, which is genuinely hard to beat for the performance difference over a standard incandescent.

Swapping the bulb will solve your immediate basking temperature problem, but while you're at it — make sure you're also running a UVB tube, not just a compact UVB bulb. For a tegu in a 4x2x2, you want an Arcadia 12% T5 HO tube running at least two-thirds the length of the enclosure. Tegus are high-UV-index animals in the wild and compact UVB bulbs simply don't produce enough output or cover enough area. If you've already got that sorted, the halogen swap is all you need for now.

Brilliant — sounds like you've got the UV side nailed then. Grab the 100W Arcadia Halogen, give it a day to settle and measure with a temperature gun or probe at basking surface level rather than in the air. Aim for 52–55°C at the spot and mid-20s on the cool end. He should be much more active and feeding more confidently once those temps are dialled in. Good luck with him.