by Merry Youle — Each au­tumn, as the leaves on the ap­ple trees in the Loire Val­ley turn from green to gold, ob­ser­vant or­chardists no­tice is­lands of healthy green within the oth­er­wise yel­low leaves. These is­lands co­in­cide with the site of leaf mines cre­ated by the lar­vae of a small moth, the ap­ple leafminer...