At first glance I thought this big brute was a hoverfly, ’cause I know there are some very large hoverflies, but one look at those eyes told me otherwise. Meet Tachina grossa, the largest Tachnid fly in Britain and Europe.

As you can see, it feeds on pollen and nectar and, though it’s harmless to us humans, it’s no friend of moths. The female Tachina grossa lays her eggs on living larvae, in particular the large hairy caterpillars of the Oak eggar moth and the Fox moth. The fly larvae eat the caterpillars from the inside, eventually but not immediately killing them.
So, it may look kind of cute in the photograph below but I’m just glad I’m not a large hairy caterpillar.

Annie, I once watched larvae emerging from a Large White Butterfly caterpillar on my window. It was both gruesome and gobsmacking. At that particular time, there were also dozens of the same caterpillars climbing up the outside of my house which was another strange phenomenon for me. Nature really is amazing.
LikeLiked by 1 person
I’ve never seen anything like that, Joyce but, yes, amazing and gruesome, in equal measures. Caterpillars get attacked by all sorts of other beasties – lots of parastic wasps do this to them too.
LikeLiked by 1 person
I’m glad you’re not a large hairy caterpillar too… 😉
Not sure I’ve ever seen one of these flies…
LikeLiked by 1 person
I’m sure you’d remember if you had, Val. 🙂
LikeLiked by 1 person