You purchase a Harpie Bug Lantern from any slayer master, you must have it equipped to do any damage to the swarm.
You can get an unlit bug lantern from any of the Slayer Masters in Runescape. You must have Level 33 Slayer to equip it and it acts as a shield and helps when fighting Harpie Bug Swarms.
They drop level 2 clue scrolls.
No, the poison itself is untradable, whereas the fish can be attained from the Grand Exchange, Gourm' Implings or Fished North of Shilo Village, slightly North East of Harpie bug swarms.
If you mean a medium clue scrolls then try killing Guards, Giant Rock Crabs, Men/Women (level-24), Tribesman, Cockatrice, Dagannoths, Harpie Bug Swarms and Rock Crabs.
not even in your dreams
Bug spray. Bug spray.
If you are having problems with Glitches in Runescape, then use the "Report a Bug" section on the Runescape Website, under Customer Support, and find out how you can report bugs or glitches on Runescape, that are causing you trouble.
Kill it
no.
no
NO
There are many ways to kill bugs.squish it,use bug spray,flush it down the toilet,step on it,let a pet kill it,fry it ,electrify it(there are electric tennis rackets)and drown it(put the bug in water ant put something heavy on top of the bug).