Grub worms can be killed or controlled by several methods, including natural and chemical options:

1. Beneficial Nematodes: These microscopic worms (like Steinernema feltiae) are applied to the soil and actively seek out and kill grubs and other soil pests. They multiply in the soil and provide ongoing control. They are an organic and effective method.
2. Milky Spore Disease: A natural bacterial disease applied to soil that parasitizes and kills grubs, especially Japanese beetle larvae. It spreads as infected grubs decay, infecting others. It works best under specific conditions such as soil temperature and grub feeding stage.
3. Bacillus thuringiensis var. galleriae (Bt): This bacterium is applied to soil, ingested by grubs, and releases a protein that interrupts their digestive system, killing them. Bt is specific, safe for other wildlife, but requires careful application and repeated treatments.
4. Chemical Insecticides: Products like Scotts GrubEx contain active ingredients such as chlorantraniliprole that affect grub muscles, preventing them from feeding, ultimately killing them. These can be used preventatively or curatively.
5. Manual Methods: Tilling soil and hand-picking grubs can help reduce population but is usually insufficient alone.
6. Other Natural Predators: Ground beetles, ants, parasitic wasps, spiders, and birds feed on grubs and their eggs.
7. Neem Oil: A natural pesticide effective against grubs and safe for pollinators.

For most effective control, beneficial nematodes and milky spore are recommended as natural options, while chemical treatments like chlorantraniliprole-based products act quickly. The choice depends on your preference for organic vs chemical methods and the severity of the grub infestation. Beneficial nematodes are often praised for controlling grubs without harming the environment. Chemical controls provide quicker results but may have broader ecological impacts. If you want detailed instructions or more specific product recommendations, please let me know. This summary is based on gardening and lawn care expert sources as of 2024-2025.