Keep an eye on the health of your colonies. There are pests, parasites, and diseases that can have deleterious effects on your colonies (see Table 5.1). There are also scavengers and others that do no harm or can actually benefit your colonies. It is important to properly identify other creatures you find residing in bumble bee colonies. Promptly isolate any colonies experiencing sudden drops in population. If reusing equipment, be sure to sterilize before reuse.
| Pests and Parasites | Damage |
| Wax moths (Galleria mellonella, Aphomiasociella, and Vitula edmandsii) | Destroys nest structure |
| Small hive beetles (Aethina tumida) | Eats pollen, destroys nest structure |
| Parasitic bumble bees (Bombus spp., subgenus: Psithyrus) | Kills queen; has colony raise her offspring |
| Parasitic wasps (Melittobia spp.) | Kills larvae and pupae; can destroy colony |
| Parasitic mites (Locustacarus buchneri) | Infects adults, transmits viruses |
| Single-celled internal parasites (Nosema bombi, Crithidia bombi, and Apicystis bombi) | Infects adults; can destroy colony |
| Internal roundworms (Spaerularia bombi) | Infects queens; can prevent egg-laying |