Chalk brood is a disease which affects honey bee larvae, caused by the fungus Acosphaera Apis. It is regarded as endemic, meaning that low levels of chalk brood are probably present in every colony, but not all colonies are badly affected by it. The dead larvae sometimes appear like small chips of chalk, hence the name chalk brood. Chalk brood is spread via fungal spores which are ingested by the larvae. The spores form hyphae inside the body of the larva which initially give it a slightly swollen appearance and a spongy consistency. The larva normally dies after being capped over, and ends up as a shrivelled "mummy" with a dark head. The body of the mummy may be white or black; the black colour is caused by the fruiting bodies of the fungus which release new spores. There are two main ways to combat chalk brood. The first is to reduce stress on the colony by keeping it warm, dry, well fed and free of other diseases. The second is selective breeding, as resistance to chalk brood can be genetically inherited.