Tachina Grossa
It’s gone rather quiet on the bird front in my garden; my attention has switched to insects – and it’s proving a fascinating focus. It started with the Big Butterfly Count that lasted for three weeks, ending last weekend, – though my sightings have been disappointingly low – a handful of small whites, two beautifully pristine small tortoiseshells, a comma and, a surprising first for my garden, a couple of gatekeepers. The latter is a medium–sized brown and orange butterfly, with darker circles containing two white spots on the corner of each forewing.
However, in doing a garden tour each fine morning to examine the buddleias, the bramble thicket and the rather untidy tangles of marjoram edging the drive, I’ve become fascinated by all the other insects that feast on the generous nectar supplies as the morning sun warms the flowers. I can recommend it as a calming and rewarding way to spend twenty minutes – longer if you want to – with the sun warming your back, drowsy humming in your ears and the wonders of biodiversity before your eyes. I can’t identify many insects without hand lens, book and a very cooperative subject. It doesn’t matter – just try noticing different visitors. The marjoram attracts bees, a lot of honeybees and a variety of bumblebees. I pick out white and buff tails, smaller workers and a few much larger queens; I can now recognize the orange and black carder bumblebees and the recent incomers to our region, tree bumblebees, orange, black and white. However, what I spotted last week defeated me – even when I had recourse to the excellent pictorial guide to bumblebees pinned to my kitchen door.
It was behaving like the other bees, patrolling the marjoram flowers and feeding on the nectar. It was black and not so much furry as sparsely hairy, and its wings had pretty amber epaulettes. Then it turned my way and revealed a bright yellow disk of a face with round black eyes. Unlike any bumblebee I had seen before.
As usual when stumped I had recourse to the WNS network. Our insect expert knew immediately what it was – not a bee but a very large fly – Tachina grossa or giant tachinid fly. It delicately sips nectar but, when it comes to reproduction, its habits are gruesome. It lays its eggs into the body of a butterfly or moth larva, thus securing a continuous fresh meat supply for its young. All part of Nature’s pattern: pollinator and parasite!
Jenny Dixon
“Tachina Grossa” photo by Corsairoz – Own work. Licensed under CC BY-SA 4.0 via Commons
