What causes a spotty brood pattern?

Also read: What does a good vs bad brood pattern look like? 

A poor brood pattern can be caused by many things. Below I’ve outlined the common causes, and how to fix them:

1. A failing queen- As queens age, they begin running out of sperm, and begin laying a more “spotty” pattern mixed with drone brood. Solution- Check out “How to tell if a hive needs to be requeened” A spotty pattern as a result of a failing queen will look spotty on every frame of brood, not just 1-2 frames. 
2. Varroa mite infestation- As a hive becomes increasingly infected with varroa, the bees will begin pulling infected larva and pupa out of their cells, causing a spotty brood pattern. Check out “Testing for Varroa” to see if you have dangerous varroa mite levels. Treating for varroa is critical if it gets to this point. You can learn how to treat for varroa here. 
3. Chalkbrood- Brood infected by the fungal infection chalkbrood will die, causing a spotty brood pattern. It’s typically found in the spring months, and is best treated with probiotics, and warmer drier weather. 
4. European Foulbrood- This disease affects the larva, and causes developing larva to look yellow and melted. It is also commonly found during the spring. Probiotics, warmer weather, requeening, and feeding can help
5. Summer- During the summer months, queens often slow down egg laying as pollen and nectar become scarce. As a result, brood can often look more spotty during the heat of the summer. It will often improve once pollen and cooler weather returns. 
6. Poor nutrition - If a hive is starved nutritionally, they will begin to cannibalize the brood, causing it to look spotty. 
7. Rapid growth & laying around resources- When the queen is laying faster than the bees can move cells of honey or pollen out of her way, she will often lay around them, causing a spotty pattern. However, you typically only see this on a few frames of brood, and the rest of the brood will look normal and compact. See picture below.