Insects have olfactory sensors on their while snakes have them on the roof of their mouths. wings feet antennae tongue

antennae

Explanation:

The olfactory sensors are the sensors which are responsible for sensing or detecting the smell. In insects the olfactory sensors are present on the antennae. These sensors or receptors binded by the molecules of the surrounding air such as water vapor, or other that imparts odours. The neurons link with these sensors will signal the stimuli of the smell to the brain.