The dew the next morning will dissolve the granules creating an extremely strong solution of the insecticide. If you water it in the flush of water will create a weaker (proper) solution of the insecticide. The strong solution from the dew can kill the lawn.

Do you always apply grub control even though you don't have grubs? Because the grub control kills off lots of beneficial insects, too. An entire class of your soil biology is called microarthropods (Latin for tiny insects). When you kill the microarthropods, the rest of the microbes (bacteria and fungi) don't have insects to feed off of. That would be like eliminating cattle from the Earth. The approach I suggest is to look for beetles to swarm your porch lights about this time of year. If you don't have that, then chances are you won't get grubs this year. If you think you might, then wait until late June and dig up 1 square foot of soil in your yard. If you see fewer than a dozen grubs, you don't have a problem. If you see an uncountable swarmy mass of movement, then you have a grub problem and should treat for it.

I have grubs. I have major Japanese beetles, moles, and damaged turf all over my yard. The damage has gone unchecked and gotten worse. I didn't want to use the poison pellets but at this point I have no choice. I didn't know about the dew

Dchall, do all grub treatments harm the soul biology or just the fast acting bayer product?

I'm anti insecticide in general.

Read this twice

Michigan State grub research prevention and cure.

FYI-The last comment by dchall_san_antonio is innacurate and is in reference to a broad spectrum insecticide which is a different product from Bayor Season Long Grub Control which again is NOT a general all species insecticide. It's specifically designed to only affect grubs by stopping their development before they mature. Its best to be watered in within 24 hours or it breaks down in sunlight. Bayor Season Long Grub Control prevents grubs, it does not kill current infestations as an insecticide like Seven would do.