One of the commonest of the protective devices is called _protective coloration_. It may be noted that many caterpillars are green, a color which blends well with that of the leaves upon which they feed, and so protects them in a measure from the prying eyes of their enemies. Such chrysalids as are attached to green leaves or twigs are often green also, but most caterpillars leave the foliage to pupate, and the chrysalids are neutral gray or brown so as to be inconspicuous against a background of bark or dead wood. Many butterflies pass the winter in the chrysalis state, and these cold weather chrysalids are never green, but usually some dull color which harmonizes with the winter landscape. Another thing to be noted, particularly in caterpillars, is the operation of the so-called _law of counter-shading_, which means simply that the part of the body which gets the most light is usually darkest in color. Some caterpillars habitually feed with their feet downward, and their backs are darker than their bellies; others are accustomed to feed in the opposite position, and the shading tones are reversed. One has only to look at a few living specimens in their native haunts to see the value of this arrangement. In adult butterflies it may be observed that it is the upper side of the wings which shows the bright colors, while the lower side is much less conspicuous. The flying butterfly is not in much danger anyway, and a display of color can do no great damage, but it might be fatal to the same insect at rest. At rest, however, the wings are usually brought together vertically, so that the highly colored upper side is quite concealed, and only the dull under surface exposed to view. In some butterflies--_Vanessa antiopa_, for example--the lower surface so nearly resembles the bark upon which the insect is accustomed to rest that it can hardly be distinguished, even when one knows exactly where to look for it. Some of these protected butterflies illustrate a minor protective phenomenon known as _dazzling_ or _eclipsing coloration_. Many observers believe that the sudden change from the bright colors of the flying butterfly to the neutral tints of the same specimen at rest is more confusing to a pursuer than the total absence of brilliant colors. This dazzling and eclipsing effect is particularly noticeable in various species of _Grapta_ and _Vanessa_.