Wednesday, 4 September 2019

Byfield trivia

Wednesday, Byfield Pocket Park. I paid a visit today armed with nothing other than a camera - not deliberately, but I left home in a rush.

Lots of flowers were still in bloom, most obviously Rosebay Willowherb, Chamerion* angustifolium. It was once known as Epilobium angustifolium (and still is, in some books) but whereas Epilobium species have actinomorphic (radially symmetrical) flowers, those of Chamerion species are zygomorphic (bilaterally symmetrical) flowers.
Rosebay Willowherb is often abundant on waste ground. Byfield
Pocket Park, 4 September, 2019

The picture shows that whereas four of the petals are broad, the fifth (lowest) one is narrow, giving the zygomorphic form. This is one of the food plants for the caterpillar of the Elephant Hawkmoth, but I searched for them in vain today.

Perhaps more important for insects are the broad, saucer-sized umbels of Hogweed, Heracleum sphondylium. With nectar accessible to even short-tongued insects the flowers attract a wide range of species, and that was the case today.

Tachina ferox on hogweed. Byfield Pocket Park.
4 September

The yellow and black tachinid fly, Tachina ferox, is a common and distinctive insect. So many were about today that in some cases an umbel was hosting two or more specimens. The caterpillars of larger moths need to beware as these flies will leave their larvae in a suitable spot; they will then parasitise a passing victim.

Two, and sometimes more, specimens of Tachina fera were present on
hogweed umbels. 4 September, 2019
Ivy flowers are beginning to open and by far the most interesting insect today was a hoverfly feeding at ivy blossom. The photograph is poor as the insect only gave me a second or two to compose my shot before flying off. Fortunately it settled again and I was able to briefly capture and examine it.

It was specimen of the Golden-tailed Hoverfly, Xylota sylvarum. It is a reasonable common but elusive species and must rank as one of our most handsome flies. It is by no means the first record for Northamptonshire but is certainly new to Byfield Pocket Park.

The best I could manage: Xylota sylvarum on ivy blossom.
4 September, 2019

And here is a slightly better (!) picture from the internet.

Xylota sylvarum. (
Finally, Dock Bugs, Coreus marginatus. It is always plentiful on dock plants and occasionally on its relatives, rhubarb and sorrel but I have never seen it is such abundance as it is this year.
Dock Bugs in abundance. Byfield Pocket Park, 4 September, 2019

It has to be said that it is not the most colourful of insects but if it drops to the ground when alarmed it is extremely difficult to spot.

* The alternative name Chamaenerion is wrong and regarded as a nom. illegit. (nomen illegitimum as Jacob Rees-Mogg would say.)

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