How to Complete Beetle in a Haystack
The objective of the battle is to find the Scarab Beetle. Lightning is forbidden, so be sure to check your weapons to make sure they are not Lightning-elemental.
Walk up to a sparkle and Investigate it to find out if it is the scarab beetle. The sparkle will disappear after you Investigate it.
As soon as you find the scarab beetle, the battle will end, so if you want loot from the monsters, don't check on the sparkles until after you get rid of the monsters.