A white grub (Phyllophaga sp.), an example of the various species of May and June beetle larvae that can affect wheat. Eggs are deposited in the soil and the hatched larvae feed on roots, which can partially completely sever them, causing patches of wilting and dying wheat plants. When fully grown, the largest of these larvae may be several centimeters long and nearly one centimeter thick.
For more information, see CIMMYT's Wheat Doctor: wheatdoctor.cimmyt.org/index.php?option=com_content&t....
Photo credit: CIMMYT.