Hello Elaine,

Thanks for your question about white grubs in your lawn!! UVM actually has a handy factsheet about white grubs that we published last year. Since you mentioned a desire to use Bt against your white grubs, it’s important to note that not all Bt products are effective against white grubs! Take a look at the factsheet, specifically the “Management” section for information about chemical and/or biological pesticides, but I’ll paste here the bit about Bt specifically since you asked about it:

Bacillus thuringiensis var galleriae (Btg): This is a bacterial pathogen that has been found to be effective against
several species of white grubs, and is sold as “grubGONE!”. Remember Bt products are somewhat specific, and
the one used against pests in the vegetable garden won’t be effective against white grubs.

There are also some good habits that you can adopt to help with control of white grub populations, to lesson the chance of future infestations. The height of mowing appears to have some impact on the size of some grub species, with smaller ones found in association with high-mowed lawns. The population of some species is reduced when lawns are not mowed too short. In general, the most significant factor affecting grub populations is soil moisture. It is generally recommended not to over-water lawns. Instead, if watering is necessary, it is better to give the grass one deep watering every few days rather than a daily light, shallow watering. Tho this advice about soil moisture is probably mute at the moment considering all the rain we’ve been getting!!

Lastly, since there are so many different species of white grubs, feel free to email us back some pictures of what you have so we can help with confirming the ID of them. 

Resource:
"White Grubs (Family Scarabaeidae): A Serious Lawn Pest” By Margaret Skinner, Ph.D., University of Vermont Extension Entomologist, June 2023