The age question needs to be answered for good help.....
Instead of killing, there is trapping and capture.
Seek , record, and report.
Material gathering for the local wizard, skill based. Climbing, rope use, ignore references to edition based terms.
No one likes ants, spiders, scorpions.
I'd say even VERY young kids don't tolerate ants.
Quick scenario for youngsters:
Local friendly/eccentric wizard summons the grp. He needs to finish an experiment he's cooking up.
To finish, he needs a sap that comes from ONE tree miles away on a hill. The sap comes from the roots ONLY.
Magic will be their's IF they get this sap.
Travel, insert various encounters as befitting X age. Cantaurs, friendly elves, mini side trek, maybe helping a centaur find an herb to help get the Centaurs wife/kid/mother get well.
On to the hill. They see a few 2-3-4 foot round tunnel openings, but no access to the roots on the top of the hill, where this one HUGE tree grows.
They go into the tunnels, only to find it's a giant ant anthill. Kill, kill, killy kill as many ants as they can stand, address the ants stats based on their ages/gaming abilities.
Give them nets, if they are seriously not into killing. Scroll of hold all monsters in an area....
They beat the ants HOWEVER they beat the ants, get the sap from roots accessible from the tunnels, head home.
The wizard adds the sap to a concoction. He then serves the group pancakes, and using the concoction as syrup which is totally magical tasting.
Ad-hoc items as befitting their age.
Deadly it up as you see fit.