Why are the grubs crawling out on top of ground and dying when no treatment to kill them?

Grubs may crawl out of the ground and die due to environmental stressors, such as drought, excessive heat, or soil saturation, which can disrupt their natural habitat. Additionally, they might be seeking better conditions or more favorable moisture levels. If their population density is high, competition for resources can lead some to emerge in search of food or moisture, ultimately leading to their demise. Lastly, natural predators or parasites could also contribute to their decline, even without direct treatment.