Monday, 28 August 2017

Unfortunate caterpillar

I took a stroll around Byfield Pocket Park earlier today. However, the main item of interest was noted just before I entered, for on a 'Lombardy' Poplar a short distance away was the caterpillar of a moth. Identifying it was not a problem for it was clearly a Poplar Grey, Acronicta megacephala. But what had happened to it?
Poplar Grey moth - but what are the egg-like objects?
Byfield, Northants. 28 August, 2017
It was still alive - just - but was surrounded by about thirty 'eggs' (not all can be seen on the photograph) and they may have belonged to a tachinid fly, several species of which are known parasites of caterpillars. The sheer mass of the eggs would surely rule out the work of a single fly so were more than one of these parasites involved? Or indeed were they tachinid eggs at all? The internet is usually helpful on these matters but gave me only a few clues and I remain puzzled. Nor, with arms at full length, could I obtain a satisfactory photograph so I brought the leaf home. Perhaps I may be able to rear some specimens.

A slightly better look.

The day was very hot and sunny but not a great variety of insects was observed. There was plenty of Bush Vetch, Vicia sepium, in flower but few bees were exploiting it. In terms of colour this species has quite variable flowers and these were of a rather sombre slate-blue.
Bush Vetch was receiving few visitors. Byfield Pocket Park.
28 July, 2017

There wasn't really a lot else: no 'oohs' or 'ahs', and the best I could come up with was a neat little trio of galls on a Grey Willow leaf. They were the work of a sawfly, Pontania proxima, a common and widespread species. I have never knowingly seen an adult of this species, but then again, sawflies aren't my field.
Galls caused by the larvae of a sawfly, Pontania proxima.
Byfield Pocket Park. 28 August, 2017
So I set off home, lingering only for a moment as I photographed a sinuous leaf mine on Hogweed. It was another exceedingly common insect, Phytomyza spondylii, and to be honest I simply photographed it because I was too lazy to take out my notebook and write it down. Shameful! But it turned out to be a new record for the pocket park.
The larvae of Phytomyza spondylii have been mining this hogweed leaf.
Byfield Pocket Park. 28 August, 2017

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