Hi Susan,

Thanks for your question - and there are non-chemical approaches you can consider:  Milky Spore and nematodes.

Milky spore works best when soils are warm - so there is some debate as to how effective they are in Northern VT.  With warming climates, and in some warmer 'microzones' they may be effective, however.  You need to be sure the grubs you have are the larvae of Japanese beetles and not some other insect as they only work for these.  You also need to treat for a few years to achieve good results.  Instructions for application will be included with the product.  You may find it locally at a nursery but you can easily find it on the internet. Here is a link to an article from University of Michigan Extension that will help with identification (it goes on to discuss chemical control unfortunately) :

https://www.canr.msu.edu/news/how_to_choose_and_when_to_apply_grub_control_products_for_your_lawn

Nematodes are microscopic worms, and some species of nematodes can work very well for controlling grubs in home lawns. To successfully use nematodes for grub control, you should keep the following principles in mind:

• The lawn needs to be well watered and the soil can’t go dry while the nematodes are getting established.

• The nematodes need to be viable (living) when applied. Purchasing nematodes from a reputable supplier and applying them right away are important.

• You need to apply the appropriate species of nematode at the appropriate time of year.

• Nematodes are sensitive to light and can be killed within a minute if exposed to intense direct sunlight – it’s generally advised to apply them on an overcast day or in the early morning.

• Some species of nematodes only control certain species of grubs, so just like with milky spore, identifying what species of grubs you have is important. Nematodes also need to be applied when the species of grubs they control are active in the soil.

• If nematodes are being used curatively, they may need to be applied every 2 weeks until the infestation subsides. For those who use nematodes preventatively, they should be applied 2 to 3 times a season.

Aribico Organics is one company I know that sells beneficial nematodes and there are probably others as well that you can compare.  

Lastly, here are some additional ideas on how to keep grubs from becoming a problem for your lawn in the future:

• Testing your soil every 2-3 years and follow the fertilizer and amendment recommendations.
  
• Keep grass mowed high – at least 2”, and ideally 3” or more – which means that your grass will have a deeper, healthier root system that can tolerate more sub-surface insect feeding.
  
• Over-seed bare or sparse areas in the spring or fall (preferred).