The external parasite among the options provided is the Ascarid. Ascarids are internal parasites that typically infect the gastrointestinal tract of animals, including pets like dogs and cats. They are roundworms that reside inside the host's body, unlike external parasites such as mites, ticks, and screwworms that live on the outside of the host's body.
1. Mites are external parasites that can cause various skin issues in animals and humans.
2. Ticks are also external parasites that feed on the blood of their hosts and can transmit diseases like Lyme disease.
3. Screwworms are another type of external parasite that infests open wounds in animals, causing myiasis.
In summary, among the options provided, the Ascarid is the only one that is not an external parasite because it resides inside the host's body rather than on the outside.
