The varroa mite is a parasitic arachnid about 1.8 millimetres long, and every year the species is responsible for countless deaths of honey bees and collapses of hives around the world. Like other mites, the varroa attaches itself to a host animal and feeds on its blood (hemolymph, in honey bees). And, like other mites, not only can it cause weakening of the host, but it can also spread diseases, which can mean disaster for honey bees who live in close quarters with as many as 60,000 in a single hive.
In a healthy hive, the infestation begins with an intruder. Often, honey bees from neighbouring colonies will invade a different hive, and once inside, if they’re carrying mites, they can spread by brushing against other honey bees. Adult mites that are ready to lay their eggs will enter a honeycomb cell and hide in the food. When a honey bee larva is sealed in the cell and begins to pupate, the mite will emerge and lay its eggs.
Over the course of the pupa’s development, the eggs will hatch and the young mites will begin to feed on it. By the time the adult bee emerges, the mites will have mated and will be ready to enter a new host cell. Once a colony of honey bees is infested with the varroa mite, they spread very quickly leading to exponential losses, especially during an overwintering period when the hive is at its most vulnerable stage.
There are many methods beekeepers can use to get rid of infestations including pesticides, heat and manual management techniques.