I counted 15 of them: small, dark moths with extraordinarily long antennae. I'd have thought them cute, but for their intense concentration on a tree that contributes substantially to our food supply. Anything that focussed and that numerous just has to be bad, doesn't it?
But what were they? Seriously hampered by the fact that they were too high to see properly, and wouldn't stay still long enough for me to snap a close-up, I first plumped for the codling moth as the main apple pest known to me, but they would be rather early. Here we were at the end of April and the RHS tells us that they emerge in late May-June (to lay eggs on or near developing fruits from June to mid-July).
Further research uncovered this Which? report on the Codling Moth which says that codling-moth damage could be mistaken for that created by the apple sawfly or the fruitlet-mining tortrix moth (they all create tunnels in the fruit).
So I investigated the latter, and bingo! Or as near as possible to bingo, given my entymological experience and the lack of a handy specimen. Here's what UK Moths has to say about the Fruitlet Mining Tortrix: "The adult moths fly from late April until June, especially in warm sunshine, around the tops of its host trees." Yup, and for a really good photo or two, see Graham Calow's close-ups at Naturespot. See the antennae?
UK Moths also says: "The larvae feed in the spun flowers and fruit of hawthorn (Crataegus), or occasionally fruit such as apple (Malus) or pear (Pyrus)." Occasionally, note. Trust me to attract gourmets.
However, move away from wildlife sites and to Dow Agrosciences, which offers products and services to solve crop production problems, and you get more of the sort of information that we fruit-producers need. Here's what to expect from the old fruitlet-mining tortrix (Pammene rhediella or FMT, as I like to call it now), which also attacks plums:
"Females lay flat, translucent eggs on the underside of rosette leaves. Egg hatch begins after petal fall. Emerging caterpillars have a black head on a white body, the head turning brown as the caterpillar matures."
Let's hope they're easy to spot. And at least the caterpillars don’t burrow directly to the core so I hope damage will be superficial. Dow Agrosciences continues: "When damaged fruit is harvested, attacked areas have a rough, corky surface and are misshapen due to reduced growth around the feeding area." Not supermarket standard, I guess, but I like my fruit to have a bit of character.
And final reassurance from another Which? report, this time on Fruit-tree caterpillars. They diverge slightly on colour (they say the FMT caterpillar is grey/green, not white or brown) but do confirm that all tortrix moths eat near the surface, producing "shallow depressions with dark margins...By harvest, the wounds will have healed, leaving a corky or russeted covering, distorting growth around the damage."
So, are those of us favoured by these little moths in for a disappointing harvest? Well, for the most part, Which? suggests not: "There are many predators of these insects."
We'll have to see whether we agree, won't we, come harvest time?