INTERESTING OBSERVATION OF PURPLE HAIRSTREAK BERRY FOODPLANT

[Devon Dave]

In the sunny weather earlier this week I had spent over an hour searching bramble blossom under a Purple Hairstreak " infested" Oak tree to try and get a close up photo of one nectaring. Not one appeared and so I was about to set off home with a failed mission when a group of walkers approached me along the rather narrow footpath I was on.
So to ensure social distancing I stepped aside off the pathway and turned to face the bushes as a Covid good practice. As they passed and thanked me I suddenly noticed several Purple Hairstreaks flitting about in the bush I was facing.
As I quickly got my camera ready two disappeared but one was still hopping around and landing near any berries on the bush. It eyed up a bunch of berries just near to where it had landed (first photo) and then flitted onto a berry, and pushed its proboscis into the berry(Second photo).
There it sat for about 2 minutes before it moved to another bunch of berries and repeated this feeding technique of pushing its proboscis either into or onto another berry. I could not determine whether its proboscis had pierced the berries or just touched the surface, but I think it was actually piecing the berries. They were impossible for me to reach to examine after the hairstreak had moved on.
He (or she) continued this feeding on berries for just over 40 minutes in total in the middle of the morning before eventually being chased off totally by a Holly blue.(third photo). I have never seen a Purple Hairstreak feeding on berries before and wonder if this has ever been observed by others ? Also I am not a tree man and do not know what the bush was with the berries on it. Any suggestions on the bush species would be appreciated. (Photo 4)

[ChrisStamp]

Very interesting. Looks like it could be alder buckthorn?

[bugboy]

It does look like Alder Buckthorn which would mean those berries are unripe and rather hard so nigh on impossible for the Hairstreak to pierce with it's tongue.

I have encountered PH feeding on overripe Blackberries on occasion:

I've also come across them licking other things, particularly early in the morning and I suspect they are trying re-hydrating after roosting before going back into the treetops (these pictures were taken in recent years when we've had extended hot dry spells during their flight period... not last year obviously!)

In this image you can see the morning dew which is being consumed:

It's possible the berry had been damaged and the Hairstreak was able to get to the flesh or perhaps the skin just tasted good or it was obtaining chemicals. I've watched a Painted Lady avidly lick a bone dry stone so they must be getting something.

[downland boy]

This is an interesting subject. We see butterflies nectaring at flowers all the time but from the flower, a fruit grows and I suspect that nectar is still available to the butterfly, up to a point, from the developing fruit. Perhaps also, the fully developed fruit may still have the scent of nectar which attracts butterflies. I have attached a couple of images of a female quercus (together with an Acorn Weevil) acting in a similar way at a developing acorn bud.


http://eastsussexwanderer.blogspot.co.uk

[Allan.W.]

You beat me to it Downland Boy ! I have several almost identical pictures to yours ,a couple of years back i also found Purple Hairstreaks on forming Acorns to which they got very attatched and got into an almost drunken state ,like Red Admirals on rotting fruit ,they also became very protective of "their " Acorn . I actually coaxed one feeding individual onto my finger and moved away around four paces,with the hairstreak still on my finger ,after a few seconds it flew ........................and went directly back to the same Acorn.

Regards Allan.W.

[Devon Dave]

Many thanks to Chris for the suggestion of Alder Buckthorn and Bugboy, Downland Boy, and Allan for the additional thoughts, photos, and information. All comments added to my person knowledge and experience bank.
This summer I will revisit the site and slit some berries with a penknife to see if it attracts them more, and report any new observations.
Devon Dave.

[David M]

These do look like buckthorn berries, and I note that the butterfly's proboscis is probing the area by the lower calyx protruding from the base of the fruit.

I wonder whether this area has trapped moisture (possibly infused with aphid honeydew that has fallen from above) as it is not smooth and rounded like the rest of the berry, and that this is what is attracting the interest of the butterfly?

[ChrisStamp]

Yes I was wondering if it is actually honeydew in all the cases. Honeydew can be sprayed around fairly liberally - for example at a location in the Scottish Borders this year, ground vegetation, fence posts, grass were all coated in it as a result of Giant Willow Aphids in the trees above, attracting many butterflies of various species to feed on the sticky coating everywhere.