Other accessories of various kinds of barns should be examined carefully and remodeled or moved if necessary to exclude rats or eliminate harbors. The haymow frequently presents a difficult problem in a heavily infested barn, but the haymow alone is seldom responsible for the rats, for if all other rat harbors in the barn are effectively eliminated or shut off, the rats will not long remain with the hay as their only shelter. If the lower walls are of rough surface or composed of open studs covered on the outside, rats can climb at the corners. They may be prevented from doing so by the application of a strip of metal 8 inches wide placed just below the joists of the upper floor. Recommended construction of walls and floors in new frame barns is shown in Figure 7. [Illustration: Figure 6.--A convenient upper-story rat-proof grain bin] [Illustration: Figure 7.--Recommended construction of walls and floors of new frame barns. Cement plaster on metal lath or Insulating board is applied to the inside of the studs at least to the level of the window sills as a better protection against rats and as being more easily kept clean than wooden lining] CORNCRIBS Of all the buildings on the average farm the corncrib is usually in greatest need of rat proofing. Losses sometimes amounting to a fourth or a third of the total quantity of corn held over winter have been known. A survey in a southern State showed an average loss of 5 per cent of corn in storage; in one case 500 bushels were destroyed in one crib during one winter. The amount of this loss would have been sufficient to pay for rat proofing the crib several times over. In building or remodeling a corncrib; therefore, it is most important that it be made permanently rat proof. Probably the most satisfactory method of accomplishing this with the common slat-sided corncrib is entirely to cover the walls and ceiling on the inside and the wooden floors on the under side with woven-wire mesh or hardware cloth, two or three meshes to the inch. A heavy grade of woven wire should be used, 12 or 15 gage, and galvanized after weaving. Painting with a tar or asphaltic paint increases its durability. [Illustration: Figure 8.--Suggested construction for corncrib: A, Section through wall; B, section through door, which is made of cribbing on vertical battens; the metal band on the wall extends across the door, but is cut and bent Inward at the edges of the door; C, plan of door; D, enlarged detail of Jamb at closing side of door]