Herein is disclosed the use of acicular wollastonite grains for killing grubsand method of making the grains. The method includes applying acicularwollastonite grains having an aspect ratio of at least about 5:1 to the groundatan area density of about 0.5 to about 6 mt per acre, with higher amounts inthisrange chosen for very bad grub infestations. The method of producing theacicular wollastonite grains having an aspect ratio of at least about 5:1,includesfeeding wollastonite feedstock into a milling apparatus in conjunction with ascreen mechanism. The milling apparatus and screen mechanism haveparameters selected to produce acicular wollastonite grains having an aspectratio of at least about 5:1, which can optionally then be fed to a cyclonewherethe acicular wollastonite grains are collected.
