I just got this slayer task and curious should i burthorpe them?

 

 

 

If not where is the best place to hunt them?

Harpie Bugs are great exp, and after a task or two you'll get thousands of fire runes. I'd take them. The only place to hunt them that I know of is the northern coast of Karamja's mainland (north of Tai Bwo Wannai Village).

keep them, they're good experience really. Not too hard to kill

I've never had them as a slayer task, but I did run into them whilst doing jungle potion quest ...my levels are lower than yours and I found them very easy and sort of fun to kill...I would do the task, just don't forget your bug light :D