Hairs!

      As someone who studies bugs for a living, one of the most difficult parts of my job is trying to convince people that the little guys should get as much attention as the big, furry, and feathery guys. There is something innately attractive to humans because fur reminds us of our own mammal ties: one of the unifying characters of being a mammal is having hairs or fur, among other things. So when we see fur, fluff, or hairs we feel a slight sense of kinship.  

Awwww!....fluffy, sleepy kitty and fellow mammal

       Well, bugs don't really have "hair" or "fur", which sets them in a slight disadvantage in that respect. Words that come to mind with bugs are "slimy", "squishy", and "gross". However, many insects have setae, which are like hairs, but since insects come from a different ancestor than mammals its actually something different. The function of the setae is also different.

Awwww?!?...fluffy-legged Clearwing moth...not mammal

        For insects, setae are often used to sense their environment around them. If a setae is bent a certain direction by a puff of air, it triggers nerves in the exoskeleton to let it know there is wind. Because insects have a hard exoskeleton rather than skin, its less sensitive to mechanical (physical) stimulation unless there is something like setae to interact with the environment. Even the hardest-shelled beetles with tough, smooth exoskeletons have setae around the joints between segments to "sense" where the other segments are and how they are moving. 

Rhinoceros beetle. If you look at the bottom of its top "horn" you'll see an example of setae for sensing when it touches something with the structure, as well as a band of golden setae below it, over its head.

        Another interesting use of setae with insects is for self defense. Caterpillars are the stars of using setae to either a.) make themselves completely unpalatable by becoming one giant cotton ball of hair, like the photo below:

Caterpillar covered in setae; its old, shed exoskeleton is to the right

         Or b.) a caterpillar can use what are called urticating hairs, which actually can cause itching and other irritation. These break off when you touch the hairs, and again help make the caterpillar as unpalatable as possible. The Douglas Fir Tussock Moth below can actually cause a significant allergic reaction if touched, or if the hairs are inhaled.

Tussock Moth. Image from http://www.fs.usda.gov/detail/r6/forest-grasslandhealth/insects-diseases/?cid=stelprdb5377760

     So...the moral of this story is that there are insects that are furry and fluffy, and may in some cases draw the same "aww, this is cute!" response as our mammalian furry friends. However, the "hairs" in insects are there for different reasons than in mammals, such as for sensing their environment or self defense against predators. Yay fluff!