Riggle is right, highly doubtful it is grubs this far north. Over my 6 years in biz, I have checked for grubs many times but never found any where I thought they may be. Hence, I have not once applied any grub treatment.
And you are as far north as we are.
7x14 Stealth SE Enclosed with 48" side ramp
08 Toro Z400 48" deck, 21HP Kaw with EZ Vac twin bag
09 Exmark Turf Tracer HP 36"
21" Toro SR4 Super Recycler
Stihl KM90 Kombi w/ straight shaft trimmer & tiller heads
Husqvarna 125B Blower
Turfco XT5 Aerator
Turfco LS-22 Overseeder
I can do all things through Him who gives me strength.