Excerpt: White grubs (Coleoptera, Scarabaeidae), the larvae of May and related beetles, are destructive pests in some young pine plantations in the Lake States Region. They live in the soil and feed on roots of trees and other vegetation. Larvae chew off the smaller and girdle the ldrger roots of pine seedlings, and consequently reduce growth, weaken, and kill the seedlings.
Recommendations against planti.ng or for control measures have been made for grub population densities ranging from 4.4/ft2, 2.0/ft.3, 2.0/ft.', down to 0.5 grubs/ft2 of soil surface (Stone and Schwardt, 1943; Rudolf, 1950; Speers and Schmiege, 1961 ; Shenefelt et al., 1954).
A study was carried out to accurately assess or predict grub-caused mortality and damage to seedlings from a given grub population density. This information is necessary for making control recommendations.
Fowler, Richard F. and Wilson, Louis F.
"White Grub Populations, Phyllophaga Spp., in Relation to Damaged Red Pine Seedlings in Michigan and Wisconsin Plantations (Coleoptera: Scarabaeidae),"
The Great Lakes Entomologist, vol 4
Available at: https://scholar.valpo.edu/tgle/vol4/iss1/5