| Moths can be found in every corner of the county but, if you look at the distribution maps, you will see that some species are found throughout the county whereas others occur in only one or two squares. Why a certain species occurs where it does can be an intriguing question. The answer is partly tied up with the availability and distribution of its foodplant, but that is not the entire answer.
Take the Grey Mountain Carpet for example. It feeds on heather; a not uncommon plant in the county. However, the heather must be growing above 300m so that restricts the available habitat to the heather moorland in the far north. We are, in fact, at the southern limit of its range. In contrast, the Foxglove Pug feeds only on foxglove and, as that is a widespread plant, so too is the moth. Being restricted to a single foodplant can have its disadvantages. The Clouded Magpie and the Dusky-lemon Sallow both feed on elms - a tree that was not uncommon in the past. However, since the Dutch elm disease wiped out most of our elms, the moths have become much scarcer and, in the extreme, could disappear altogether. Some distributions are harder to explain. Why, for example, does the Scorched Carpet, which feeds on spindle, occur at sites where spindle has not been found? The Juniper Pug feeds, not surprisingly, on juniper. However, Edees' Flora shows that wild juniper does not occur in the county, yet the moth is quite widespread. The answer, of course, is that the species has taken to feeding on garden cultivars and it is we who have aided its spread through the county. The same can be said of the Juniper Carpet, Freyer's Pug and Blair's Shoulder-knot. Many species are found all over the county and these are usually non-specialist moths, feeding on a wide variety of common plants or "weeds". Others, like the Grey Mountain Carpet mentioned earlier, feed on common plants but only in certain habitats. The Bulrush Wainscot feeds in the stems of reed mace and, as this plant is found in marshy areas and reed beds, so too is the moth. Likewise, the Barred Red, Pine Carpet and Spruce Carpet feed on conifers and so are usually found in and around pine woods. This restriction to habitat and foodplant can be of use when you are puzzling over the identification of a new or rare species of moth. If you are not sure of your identification, ask yourself if the habitat and foodplant availability are right for the species in question before claiming it.
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