Saturday, 16 July 2016

Post 431 - Happily Humming & Hovering - The lifecycle of hoverflies

Adult Hoverfly - this one is a Sunfly 
Hey everyone, Post 431 and a little break from petitions and pollution with today's post, though I am totally amazed that my petition about wildlife laws has got to an amazing and quite pleasing number of 1,234 signatures as I write this!

You might remember back in 30 days wild, and as part of National Insect Week, that I went on a bug hunt with a fantastic entomologist, Dr. Roger Key. Amongst all of the things that we found were a couple of hoverfly larvae. Well Roger suggested I have a go at raising them so I did, and it gave me the chance to get lots of photos that I could use to explain the lifecycle of these wonderful insects.

I love seeing these insects. I see quite a lot of different species and it's the right time of year to see them too. I have seen quite a lot in the forest I go to quite often, Silton Forest, where there are quite a lot of umbeliferous plants at the right height for me to get a good look at them!

So, on to their lifecycle.
    video
  • They start out as eggs. Adult females lay their eggs on the bits of plants that the larvae  will feed on or find food on when they hatch.
  • Some larvae are predators and will eat aphids, mine was. In fact it was very predatory. I found two larvae and put them in the same pot to take them home, but there was only one by the time I got home!
  • Predatory hoverfly larvae are great for gardens and allotments as they eat aphids. I get a lot of hoverflies in my garden and it was quite hard finding aphids to feed this one on after a while. In the little video here you can see a cheeky aphid hitching a ride on the larvae!
Does this count as a packed lunch?
  • Not all hoverfly larvae are predatory though. Some eat plants. The adults lay the eggs near to the bit of the plant they like to feed on and the larvae when hatched tunnel into the roots, stems or leaves where they feed.
  • Some larvae have a different diet and they like rotting or decaying plant matter. Some of these live in stagnant or polluted pools and have a special tube which they use to breathe. These larvae are called rat tailed maggots.
  • So the eggs hatch, the larvae feed on their favourite foods until they reach the next stage of their development. This can take up to a year for some species, but quite a lot shorter for some like mine.
    Pupating - you can see some markings developing
  • When they are ready to pupate the larvae releases fluid from its bottom that it uses to stick itself to the place it will pupate.
  • It then turns itself into a pupa, not quite sure how that transformation happens but it can take a few days for the pupa to become hard.
  • Inside the pupa the larvae undergoes an incredible transformation. You can see in my pictures that you can see in the later stages the markings appearing in the pupa.
  • When the transformation is complete the adult breaks out of the pupa and has to find a clear space to pump up its wings and allow them and its body to harden off as it is quite soft when it emerges.
    Emerged and pumping up the wings, the pupa case
    is in the background.
  • The adults are then ready to start the process again. They fly off to feed on nectar and are important pollinators, and they look for a mate.
So that's their lifecycle. It was great to be able to watch it close up and I was quite surprised how quick it was. It was a good job I took my jar with me when I went to the Big Bang Fair as that was the day that the adults decided to emerge. It was a very good thing to have a talk about too and lots of people were very interested in it.

I hope you enjoyed,

Zach

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