Cryptic Apple Leaf-miner Phyllonorycter hostis

Formerly given the vernacular name Red Apple Midget.

This is one of several similar species that require examination of the genitalia to identify with certainty. Most references don't explicity state the differences in genitalia so even this can be problematic. The male genitalia of Phyllonorycter hostis share a number of characteristics with Phyllonorycter oxyacanthae, specifically both have one costa much longer than the other, both costae have a terminal spine on both and on the longer costa the spine is curved. I recently identified a moth as hostis due to the sharpness of the curve of the terminal spine on the long costa and the length of the spine on the other, this despite me having expected the moth to be oxyacanthae due to finding it close to Hawthorn. When I examined the following moth I noted that images of genitalia of both species in fact showed quite a bit of variation in both characters, and I couldn't see why the original one wasn't oxyacanthae as I had originally suspected. I have therefore removed it from this page. The following one was quite a large moth (forewing 4mm without the terminal cilia, so wingspan must have been over 8mm, probably around 9mm, and was netted flying around what I thought was an apple tree (not sure what type of apple and could well have been Crab Apple).

Reluctant to eliminate oxyacanthae purely on size (and possible tree association, but you wouldn't have to go far to find Hawthorn), I tried to find reliable differences in the genitalia. I'm not sure I've found them, but these seem to be fairly consistent and together with the size I think it adds up to enough to call this hostis. There seems to be some variation in the thickness of the long costa, but it seems that this is usually thicker in hostis. Also the valvae seem to be thicker in hostis compared to oxyacanthae, and more evenly broadly rounded at the tip. Allowing for differences in how flat the valvae are lying in the preps this seems to be quite consistent I think, though this is based on a relatively small number of photos. Also the long costa (including its spine) is longer in oxyacanthae, not as long as the valva but approaching this, whereas in hostis it is much shorter than the valva. If I'm right in interpreting these differences then the following specimen is indeed hostis and the previous one was oxyacanthae.

male Cryptic Apple Leaf-miner Phyllonorycter hostis showing genitalia, Beetley Meadows (Norfolk, UK), 28th April 2025