Sep 182015

Last week, on Thursday evening, our group talk was entitled “Insects – Life styles and Life cycles” by Mike Chittenden. Here is my own take on that subject.

caterpillarOn the 26th August 2014 Julie brought me an elephant hawk-moth caterpillar that she had found eating the leaves of a fuchshia in her garden. The caterpillar had been OK when she found it but it now looked rather “unwell”. Caterpillars sometimes change colour when they are about to pupate – and this one would have done so just below the soil surface. I can’t remember now why – but I decided the caterpillar was parasitised and I decided to have a look inside to see what was happening.tachinid edit (13) I made a small incision in the cuticle and Sally took all of the photographs and video. You can now see what we saw. The bright highlights are caused by the LED ring lighting. Watch the video (allow your dinner to go down first!). How many larvae can you see?

The elephant hawk-moth caterpillar had been parasitised by a tachinid fly. The biology of this group of flies is very varied but, in general, the larvae of the fly feed inside the host’s body. They are probably prompted to start feeding when the caterpillar stops feeding and seeks a pupation site in the soil. So the feeding activity of the fly larvae usually takes place out of sight.

By the next morning the fly larvae had pupated in the soil. tachinid pupae edit2)I kept them in my outside laboratory (shed) and the flies emerged in June 2015. TachinidI retained one of the flies and sent it to Laurence Clemons, the leading Dipterist in Kent, and he identified the fly as Drino lota (Meigen, 1824). It turns out that this species is not reported very often – to find out more about this species and its distribution have a look at this tachinid website.

And all of this started in Julie’s garden on her fuchsia plants. Now you know what fuchsia is really for!


 Posted by on 18 September 2015 at 10:57 pm

  3 Responses to “The Life Cycle of a Tachinid Fly”

Comments (3)
  1. Fascinating stuff. It’s incredible to think that all these unseen and sometimes rare creatures can be in a garden.

  2. Prompted by Laurence I searched my notes for more data. The fly that I retained emerged on 17th June 2015. I also searched through the soil/sand medium that the flies had pupated in and found nine puparia (so there were nine larvae.

  3. That is brilliant! Excellent photos too Sally

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