If you're looking for lost arrows with a metal detector, it's important to know what kind of metal your arrow is made out of. If the arrowhead is made from a ferrous metal like iron or steel, then it will be detectable by a metal detector. However, if the arrowhead is made from a non-ferrous metal like aluminum or brass, then it will not be detectable. In general, it's best to look for lost arrows in areas where there are likely to be ferrous metals present - such as near fences or in tall grass.