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Banana Moth Opogona sacchari

Also known as Sugar-cane Moth. Banana Moth Opogona sacchari and Eastern Detritus Moth Opogona omoscopa are two closely-related adventive moths that are occasionally recorded in England. The latter is established in Scilly (only?) but as far as I know the former has not been proven (or suspected) as breeding in the wild. Neither species had been recorded in Norfolk prior to the following two.


David Bratt contacted me in August 2025 about a suspected Opogona sacchari that he had caught in Fakenham and been advised to get it gen detted for confirmation. He brought the moth round to me and before gen detting it I decided to take some photos. It was compliant throughout its photoshoot and once I'd finished I carefully placed the pot back over it. It was secure, or almost so, for I still had to put the lid on the pot. I did so carefully, but to my horror it somehow managed to slip out as I placed the lid over the pot, immediately disappearing behind my filing cabinet. All efforts to relocate it failed, so much to my embarrassment I was unable to confirm it. Subsequent events, described below, have led me to conclude that despite not confirming it genitalically, this can nevertheless be safely identified as Norfolk's first Opogona sacchari.

Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari
Banana Moth Opogona sacchari, Fakenham (Norfolk, UK), 27th August 2025 (collected by David Bratt)


Fast forward to July 2026 and Steve West contacted me about a suspected Opogona sacchari that he had just caught at Walpole Highway. This time it had died by the time I received the specimen, so no chance of it flying off! But specimen secured, the identification process was still not straightforward. What are the differences, genitalic or otherwise, between the two species? I struggled to find much useful literature showing or describing the differences, and what about other species of Opogona? What I did find didn't consistently marry up with photos online. Eventually I have concluded that identifying sacchari is actually quite straightforward, but an error in the literature has led to some misidentifications which confuse matters considerably. Here are the references I have referred to:

There are other references that may be helpful but are behind paywalls, but the references I've seen seem to be agreed that Opogna sacchari is distinctly larger than all other members of the genus, and both David's and Steve's moths should be sacchari based on size. David has been able to calculate his moth's wing length by measuring the surface it was on, and it had a wing length of approximately 11mm, and I measured Steve's moth's forewing to be 11.6mm, both comfortably within range for sacchari and outside of the reported size ranges for omoscopa.

According to the European and Mediterranean Plant Protection Organization Diagnostics PDF for Opogona sacchari, adult sacchari "can be positively identified by the genitalia and unique hair-pencil", however according to Davis & Peña (1990) the hair-pencil is shared with omoscopa: "By its relatively large size and predominantly brown color, Opogona sacchari is easily distinguished from nearly all other members of this large complex. Its affinities are with O. omoscopa (Meyrick) as suggested by their similar male genitalia and shared presence of a dorsal hair pencil in the hindwings of the male." Gaedike & Karsholt (2001) also state that the hair pencil is shared with omoscopa (but no other Madeiran Tineidae). Given that Steve's moth has the hair pencil and genitalia that are similar to both sacchari and omoscopa, I think it's safe to rule out other Opogona species.

Both David's and Steve's moths show a similar pattern of pale and dark streaks along the wing and a large dark discal spot about three quarters of the way down the wing (more obvious on Steve's) and a weak suggestion of a dark spot nearer the dorsum and nearer the base. According to Gaedike & Karsholt (2001), omoscopa has "darker forewings [than sacchari], with a yellowish tinge and a characteristic yellowish tornal spot." This description of omoscopa accords with all of the photos of omoscopa on Lepiforum, none of the sacchari on Lepiforum, all of the omoscopa from Scilly at British Lepidoptera and the omoscopa from Devon but not the photos of three moths identified as omoscopa from Worcestershire (two featured on the West Midlands Moths website) or Cleveland (featured on both the Yorkshire Moths and Hants Moths websites). Photos of sacchari vary, many showing the distinctive longitudinal streaks but many with a plain background, many showing both discal and baso-dorsal spots but others lacking one or both of these. None show the pale tornal spot described for omoscopa. If we ignore the Worcestershire and Cleveland moths, external differences between the two species seem consistent with published descriptions (allowing for variation within sacchari) and both David's and Steve's moths both clearly resemble sacchari and not omoscopa. Unfortunately if we assume that the Worcestershire and Cleveland moths are identified correctly as omoscopa, this puts a spanner in the works as all three of those resemble sacchari not omoscopa and one (from Worcestershire) roughly resembles David and Steve's moths.

So we turn to the genitalia. Most of the references I've found show genitalia for one of the two species but not both, and although the European and Mediterranean Plant Protection Organization Diagnostics PDF states that sacchari can be positively identified by the genitalia none of the references are explicit about how. Gaedike & Karsholt (2001) does show genitalia for both species but there is a significant error here: the aedeagus illustrated for sacchari is not an aedeagus at all. This error was subsequently admitted by Gaedike by email, quoted (in German) at Lepiforum. The context was the reidentification of genitalia from omoscopa to sacchari and Google Translate's translation is:

In an email to E. Rennwald dated November 9, 2017, Reinhard Gaedike explained: "The moth and the genitalia are *sacchari*. I have already written to Ruedi stating that the confusion was 'caused' by me, because in the Madeira paper I identified a structure in *sacchari* as an aedeagus—which it is not; I do not know what it actually is. The shape of the valvae is significant for distinguishing the two species: in *sacchari*, the costal part has an oval tip, whereas in *omoscopa* the costal part is narrow and of roughly uniform width; the ventral part has a hook-shaped tip in *sacchari*, but a pointed tip in *omoscopa*." So this offers two differences in genitalia: the valvae are oval at the tip in sacchari and narrow and of uniform width in omoscopa, and the sacculus has a hook-shaped tip in sacchari, pointed in omoscopa.
These differences are clearly illustrated in Gaedike & Karsholt (2001) (the Madeira paper referred to in the quote above) and consistent with the diagrams of omoscopa in Davis (1978).

Some caution needs to be applied when assessing the shape of the valvae as this varies according to the angle. On Steve's moth the tip of the valvae looked almost diamond-shaped at some angles but broadly rounded at other angles. However, the photos of sacchari genitalia at Lepiforum and Steve's are all consistent, so far as the shape of the tip of the valvae is concerned, with Gaedike & Karsholt's description and diagrams for sacchari. Moreover all the photos of omoscopa at British Lepidoptera are consistent in respect to the shape of the tip of the valvae with Gaedike & Karsholt's description and diagrams for omoscopa. Moth Dissection shows genitalia of three omoscopa, individuals from Hampshire, Worcestershire and Scilly, however while the two from the south coast show relatively narrow parallel-edged valvae, the one from Worcestershire is broad and oval like sacchari.

Similarly, some caution is required when assessing the shape of the tip of the sacculus. Any curvature (the 'hook') becomes more or less evident depending on the angle, and generally less evident when flattened under a cover slip. For example one of the photos of sacchari genitalia at Lepiforum does not show the hook at all, although perhaps the distortion of the hook is hinted at by the concavity of the ventral margin. None of the photos of omoscopa genitalia at British Lepidoptera show a hook (a slight curvature on one) and neither of the south coast examples at Moth Dissection do either. These also show a more triangular tip, not as produced (regardless of curvature) as on sacchari. Again the Worcestershire example at Moth Dissection is anomalous, showing a more clearly produced tip on one side and a more clearly hooked tip on the other. Steve's moth is consistent with sacchari, showing a clearly hooked (very obvious before setting) and produced sacculus.

Another difference in genitalia seems to be the position of the row of thorns on the edge of the uncus lobes - these start close to the upper corner of the lobe omoscopa and clearly distant from the corner in sacchari. This difference seems to be consistent with all diagrams and photos - again with the exception of the Worcestershire individual.

I asked Google for differences between the two species' genitalia and it gave me different results on different days, and was also unable to provide sources for what it claimed (or rather, it did tell me the sources, but the sources didn't actually say that). Anyway, it suggested differences in the shape of the tip of the saccus (truncate vs. rounded) and in the curvature and length of the aedeagus. I am not convinced about either, although the former is easily distorted so would be hard to assess and the latter (curvature at least) depends on which way the aedeagus is oriented). It also suggested a difference in the distance between the uncus lobes which may be correct but as this is subject to distortion too, I'm not sure how useful it is.

There does seem to be one difference in the aedeagus. Most of the diagrams of sacchari aedeagus show not only the sclerotised shaft but also a distinctive large membranous sac basal to the shaft. One of the photos at Lepiforum shows this, and so does Steve's moth. One of the other photos at Lepiforum doesn't show the sac, but does show the base of the shaft expanded as it is in the diagrams and on Steve's moth. This is not really evident on the other photo at Lepiforum. None of the diagrams or photos of omoscopa show the sac or the expansion at the base of the shaft - it's easy to imagine that the sac would have been removed during preparation but the sclerotised expansion at the base is unlikely to be lost (although the single photo at Lepiforum that doesn't show this might suggest that it is not visible at some orientations or on every indvidual). Note that the Worcestershire genitalia photo at Moth Dissection does not appear to include the aedeagus.

One of the photos of omoscopa genitalia at Moth Dissection shows the seventh sternite, and this is also illustrated for omoscopa in Davis (1978). I haven't found any illustration or description of this for sacchari, however Steve's moth seems to shows a tidy comb of evenly-lengthed hairs on the lobes, quite unlike the messy bussle of hairs shown in the photo and diagram of omoscopa. Some hairs may be lost during cleaning (there are fewer on one lobe than the other on Steve's moth, presumably for this reason) so it's not entirely clear if this is consistent, but I am pretty sure Steve's moth never had the large bussle of hairs shown by omoscopa. The lobes also seem to be broader at their tips, and the notch between them not so deep.

In conclusion, I find it hard to see how the first Worcestershire moth cannot be misidentified, and I believe it is in fact Opogona sacchari. Given the experience of the determiner I can only assume he was misled by the erroneously illustrated aedeagus in Gaediek & Karsholt. This was the only photo I found purporting to be omoscopa that had obvious pale longitudinal stripes. I also consider that the second Worcestershire individual and probably the one from Cleveland are better matches for sacchari on external appearance and would suggest that it might be worth re-examining the genitalia and/or specimens for all UK records of Opogona omoscopa away from the south coast. If indeed the Worcestershire record is misidentified, then there is no remaining evidence to suggest that the external appearance of either David's or Steve's moths are compatible with omoscopa, nor the genitalia of Steve's.

Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari Opogona sacchari
male Banana Moth Opogona sacchari showing length of forewing, right wings from above, right wings from below, hair pencil at base of hind wing, hind leg, genital capsule in situ from side, genital capsule at 3 orientations before setting, saccus before setting, 2 views of aedeagus before setting, set genitalia, set saccus, set aedeagus (entire and close-up of sclerotised section) and subterminal abdominal segment, Walpole Highway (Norfolk, UK), 10th July 2026 (trapped by Steve West)






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All photos are copyright Dave Appleton - please do not use them without obtaining prior permission.