The BEL Complex Explained: How to Breed Blue Eyed Leucistic Ball Pythons

Blue Eyed Leucistics are some of the most striking ball pythons you can produce. Pure white (or nearly white) snakes with bright blue eyes. But getting there requires understanding which genes work together and how to combine them.

Here's everything you need to know about the BEL complex.

What Is a Blue Eyed Leucistic?

A BEL is a ball python that appears white or mostly white with blue eyes. Unlike albinos (which lack melanin and have red eyes), leucistic snakes have a partial loss of pigment that affects all color types.

The "blue eyed" part is important. There are other white ball pythons (like Ivory from the Yellow Belly complex), but BELs specifically have those distinctive blue eyes.

BELs aren't a single morph you buy and breed. They're the "super form" produced when you combine two genes from the same genetic complex.

What Is a Complex?

A "complex" in ball python genetics means a group of genes that share the same chromosome location (allele). Because they share the same slot, you can only have a maximum of two of these genes in any single animal.

Think of it like having two parking spots. Each gene in the complex wants the same spots. You can have:

• One copy of Gene A (heterozygous for A)
• Two copies of Gene A (homozygous for A, or "super" A)
• One copy each of Gene A and Gene B (combination)

You can NOT have Gene A + Gene B + Gene C in the same animal if they're all in the same complex.

The BEL Complex Morphs

These are the main genes that can produce Blue Eyed Leucistics when combined:

• Lesser Platinum (often just called "Lesser")
• Butter
• Mojave
• Russo (Het Russo / Russo line leucistic)
• Mocha
• Phantom
• Bamboo

When you breed any two of these together (or breed one to itself to make a "super"), you can produce a BEL.

How to Make a BEL

Any pairing of two BEL complex genes gives you a 25% chance of producing a BEL per egg.

Example: Mojave x Lesser

Let's call Mojave "M" and Lesser "L". Both parents are heterozygous (one copy of their gene, one normal).

	M (Mojave)	n (normal)
L (Lesser)	ML (BEL!)	Ln (Lesser)
n (normal)	Mn (Mojave)	nn (Normal)

 

Results:

• 25% Blue Eyed Leucistic (Mojave + Lesser combined)
• 25% Lesser
• 25% Mojave
• 25% Normal

The BEL is the combination animal. It carries both genes and expresses the leucistic phenotype.

What About Super Forms?

You can also make BELs by breeding two of the same gene:

Example: Mojave x Mojave

• 25% Super Mojave (BEL)
• 50% Mojave
• 25% Normal

The "Super Mojave" is technically a BEL, but it often has some coloration that cross-complex combinations don't have.

Which Combinations Make the Cleanest BELs?

Not all BELs come out pure white. Different combinations produce different results:

Cleanest (Most White) Combinations

• Lesser x Mojave - Generally produces very clean white BELs
• Lesser x Butter - Clean white
• Butter x Russo - Tends to be pure white with bright blue eyes
• Super Lesser - Clean but can have bug eyes (see notes below)
• Super Butter - Clean but can have bug eyes

Less Clean (May Have Coloration)

• Super Mojave - Often has a grey/black smudge on the head and yellow speckling down the spine
• Phantom x Mojave - May have more color variation
• Phantom x Mystic - Creates "Mystic Potion" which has some color, not pure white

If you want the whitest possible snake, stick to Lesser, Butter, Mojave, and Russo combinations.

Important Notes and Cautions

Bug Eyes in Super Lesser / Super Butter

Super Lesser Platinum and Super Butter can sometimes have "bug eyes." The eyes appear larger or slightly protruding. This is cosmetic and doesn't affect health, but some breeders prefer the cross-complex combinations (Lesser x Mojave, etc.) to avoid it.

Lesser vs. Butter: Are They the Same?

This is a long-running debate. Lesser and Butter look extremely similar and produce similar results when combined with other morphs. Some consider them the same gene; others note subtle differences. For practical BEL breeding purposes, they behave the same way.

No Wobble Concerns

Unlike Spider and Champagne morphs, the BEL complex genes do NOT carry wobble or other neurological issues. BELs are genetically healthy snakes.

BELs Bred to BELs

If you breed two BELs together (both being Super Mojave, for example), all offspring will be Super Mojave BELs.

If you breed a Mojave/Lesser BEL to another Mojave/Lesser BEL, you'll get a mix of Super Mojaves, Super Lessers, and Mojave/Lesser BELs. All white, just carrying different gene combinations.

BELs Bred to Normals

Breeding a BEL to a normal ball python produces no BELs in the first generation.

Example: Mojave/Lesser BEL x Normal

• 50% Mojave (single gene)
• 50% Lesser (single gene)

All babies carry one BEL complex gene but none are BELs themselves.

Planning Your BEL Project

If you want to produce BELs, here's the basic path:

Starting from scratch:

1. Acquire two different BEL complex morphs (e.g., one Mojave, one Lesser)
2. Breed them together
3. Expect 25% BELs per clutch

Budget option:

1. Acquire one BEL complex morph
2. Breed it to a normal
3. Keep a het offspring
4. Breed original parent to offspring (line breeding)
5. Expect 25% BELs

Fastest results:

1. Acquire a BEL
2. Breed to any BEL complex morph
3. 50% BELs per clutch

Adding Other Genes to BELs

BELs can carry additional genes that don't visually express on the white snake but can be passed to offspring.

Example: A Pastel Mojave Lesser BEL is white with blue eyes, but carries Pastel. Breed it to another Pastel, and you can produce Pastel Mojaves, Pastel Lessers, Super Pastels, etc.

This is valuable for breeders who want to use BELs as part of larger projects without "losing" other genes in the process.

Tracking Your BEL Complex Animals

Once you start working with BEL complex genetics, tracking which animals carry which genes matters. A Mojave/Lesser BEL looks identical to a Butter/Russo BEL, but they'll produce different offspring.

THE RACK lets you record the exact genetic makeup of each animal, including which BEL complex genes it carries. The genetics calculator shows you expected outcomes for any pairing, helping you plan which combinations will give you the cleanest BELs or set up future projects.

When you produce a clutch, you can track which specific gene combination each BEL carries, even though they all look the same. That documentation becomes essential when those BELs go into your breeding program later.

The Bottom Line

BELs are produced by combining two genes from the BEL complex (Lesser, Butter, Mojave, Russo, Mocha, Phantom, Bamboo).

Key points:

• Any two BEL complex genes can produce a BEL
• 25% odds per egg when breeding two single-gene animals
• Lesser x Mojave and similar crosses produce the cleanest white snakes
• Super Mojave may have head coloration
• Super Lesser/Butter may have bug eyes
• No wobble or health issues in the BEL complex

BELs are beautiful, healthy, and relatively straightforward to produce once you understand the genetics. Track your animals' exact gene combinations, and you'll know exactly what to expect from every pairing.