Hornworms are not harmful to humans. However, they can cause damage to plants. The eggs and larvae are very destructive. They eat grass, soil, and roots. They can also kill plants.
A hornworm may bite if it feels threatened or cornered. They also may bite if they are hungry. If they are hungry, they may be trying to feed on the roots of a plant.
The most common cause of a hornworm bite is in the spring. The adults are out looking for food and the young ones are out looking for mates.