Tachinid Flies

There are more than 8000 members of the family Tachinidae that can be identified and it is understood that there are many more that haven’t been identified yet. Very few of them have common names and of all of those species there are only a handful that you or I would be capable of identifying to species. Today I am going to show you two of them.

Tachina fera first.

Tachina feraTachinid flies are endoparasitoid.

Just so that we all understand:

A “parasite” lives on or inside it’s host without killing it, like a flea or a tapeworm. A “parasitoid” kills it’s host and “endo” just means that it lives inside the hosts body rather than on the outside.

The larvae of Tachinid Flies live inside a host insect, they eat it and ultimately kill it. The way that they get inside their host varies, some tachinids inject their eggs into the host’s body, others glue them to the outside of the host with a bond that cannot be broken without killing the host. (Superglue) and there are others that lay eggs on a plant for the host to eat.

Tachina feraNature has a balance.

Tachinid Flies are extremely good news for plant life. The adults drink nectar and they are very important pollinators. They  can live in places that other pollinators can’t. They can live at very high altitudes for instance. They also kill insects that would otherwise eat plants.

To the green or organic grower tachinids are a valuable natural pest control allowing us to avoid the use of pesticides.

I have even heard that in North America non-native tachinids have been released for the purpose of organic pest control. Using these flies in that way is a bit risky in my view as most of them are not host specific, they attack more than one particular species and it involves making a decision to alter nature’s balance and a belief that you fully understand the consequences of doing so.

To the organic gardener though, you can attract tachinids by planting nectar rich species and they will help to control pests in your garden.

Tachina feraTachinid species attack all kinds of insects including beetles, sawflies and also the larvae of butterflies and moths. Tachina fera is a parasitoid of various moth species including the Small Quaker, Broom Moth and Dun-Bar.

Tachina feraSo why are Tachinids in the news today?

Well, it is hard to go searching for Small Tortoiseshell Larvae without noticing the activities of our next fly Pelatachina tibialis.

Pelatachina tibialisIt is a parasitoid of the Small Tortoiseshell and Peacock butterflies amongst others.

Sometimes I just look and think, why does that have to happen, butterflies don’t do any harm? Sometimes I don’t know the answer.

Pelatachina tibialisIt is plain that Pelatachina tibialis is a valuable ally of the Stinging Nettle, the caterpillars do a lot of damage to the plant. It is also obvious, from poking around in the nettles that a whole lot of different species are dependent on Nettles and so, there is the balance.

Pelatachina tibialisEverything out there is there for a reason and everything has a job to do. They are all inter-connected and inter-dependent.

Natural science is very good at telling a Panda from a Polar Bear but we don’t fully understand the social structure of a Badger Clan yet and we hardy know anything at all about Pelatachina tibialis or what it is doing here. Sometimes you just have to have faith.

Pelatachina tibialisNature is very cruel, it has no empathy.

At least we have saved Treacle from being weighed in those scales.

Pelatachina tibialis


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