Earwigs eat aphids and several other harmful pests as well as hosta leaves. Some gardeners put up with the damage and leave the earwigs in the garden to control other pests. You can control earwigs with traps. Place a piece of crumpled paper under a flowerpot or use a tube of paper or bamboo as a trap.
In optics, refraction is a phenomenon that often occurs when waves travel from a medium with a given refractive index to a medium with another at an oblique angle. At the boundary between the media, the wave's phase velocity is altered, usually causing a change in direction.
The index of refraction for the ordinary ray is constant and is independent of direction. The index of refraction for the extraordinary ray is a continuous function of direction. The index of refraction for the ordinary ray is independent of direction. The two indices of refraction are equal only in the direction of an optic axis. The measure of birefringence (Î´) [delta] is the difference between the indices of refraction of the two rays.