Bluetongue virus (BTV) is an arbovirus, meaning that it is transmitted by arthropods, such as mosquitoes and midges. BTV is not known to survive the winter in its free form. Instead, it survives by overwintering in infected animals, or in the eggs of infected mosquitoes or midges.

In infected animals, BTV can remain dormant for several months. When the weather warms up in the spring, the virus becomes active again and can be transmitted to other animals by biting insects.

In the eggs of infected mosquitoes or midges, BTV can survive for up to 2 years. When the eggs hatch in the spring, the newly emerged insects can transmit the virus to other animals.

BTV can also survive in frozen semen, which can allow the virus to be spread to new areas by the movement of infected animals or semen.