Chrysoperla pallida

This species was split from the extremely similar Chrysoperla carnea after the publication of Plant's key. See Henry, Brooks, Duelli and Johnson (2002)¹ for details. I am not aware of any confirmed records of this species in the UK north of Essex prior to 2022 but there were a couple of credible but unconfirmed reports in west Norfolk in 2016. The same observer caught another in 2022 and this time retained the specimen which does indeed appear to be pallida.

After examining the abdomens of over 400 male Chrysoperla carnea in the hope of finding a pallida, I finally found what seems to fit pallida in 2023. The shape of the abdomen on live Chrysoperla can appear to change slightly, so that an individual that appears to be ambiguous on initial examination can be more obviously carnea on a subsequent examination. Occasionally I've even caught individuals that looked like they might be good contenders for pallida at first, but when I've looked at them a second time they've been carnea. The one below looked very promising on first examination, and continued to do so each time I re-examined it. Not only was the shape right, but it was also very striking to see how the lip lacked any long hairs at all, quite different from any of the 400 male carnea I have examined. Clearing the abdomen in potassium hydroxide can help to see the shape more clearly, and after doing this I remained happy that the shape matched pallida. I was unable to detect any differences in the internal structures compared to carnea. Viewed from above and below, the end of the abdomen appeared to be slightly flatter compared to a carnea I was examining at the same time - even slightly notched from above. However, I have not checked many carnea from these angles so I'm not sure if that is relevant to the ID or not - something to investigate in future perhaps.

On the majority of carnea, some of the long hairs on the lip (as well as elsewhere on the abdomen tip) are dark, but this is not always the case - some can have entirely pale hairs on the lip. The lip hairs are normally pale on pallida, but it is not safe to identify pallida based on this character as it can be matched by carnea. It has been suggested that pale hairs on the underside of the abdomen might be a useful character for pallida too, but I think this is quite common on carnea too (it's also typical on lucasina which has an abdomen structure similar to carnea).

It's also been suggested that a narrow dark bar in front of the eye may be useful for identifying pallida. If so then it's not simply the presence or absence of the bar as carnea also has, to a lesser or greater extent, a dark bar here. I examined this character on a series of over 20 carnea recently and there was quite a bit of variation. None were precisely the same shape as on this pallida, so there may be something in this, but if so I think it needs more work to define exactly what we should be looking for.

¹ Henry, Brooks, Duelli and Johnson (2002). Discovering the True Chrysoperla carnea (Insecta: Neuroptera: Chrysopidae) Using Song Analysis, Morphology, and Ecology by Henry, Brooks, Duelli and Johnson in Ann. Entomol. Soc. Am. 95(2): 172-191 (2002) (can be downloaded here).

male Chrysoperla pallida showing forewings, close-up of mid costa, face, abdomen tip from side (before and after clearing), abdomen tip from below (cleared) and abdomen tip from above (cleared), North Elmham (Norfolk, UK), 10th October 2023