Guess who’s coming to dinner …

Walking round my garden here in York yesterday, what did I come across but my old friends (and world-first insect discovery), Berberis sawfly larvae (Arge berberidis)! Munching away at my berberis. For the fourth consecutive year.

Recently hatched Berberis sawfly larvae, York, 23 June 09

Recently hatched Berberis sawfly larvae, York, 23 June 09

They looked like they’d hatched only recently – as you can see here. Which is just about the same time as they hatched last year. (Read all about it)

I looked around carefully, and found some leaves with Berberis sawfly eggs laid in ‘pockets’ inside them. (Click here to watch my video of how they do this.) As in previous years, the adult sawflies seem to favour laying more than one set of eggs on the same leaf.

Berberis leaf with Berberis sawfly eggs, York, 23 June 2009

Berberis leaf with Berberis sawfly eggs, York, 23 June 2009

And talking of adult sawflies, I looked around some more, and saw two skittish adults. Who seemed to be casing the berberis bush, trying out different leaves to find one that took their fancy for egg laying.

Adult berberis sawfly (Arge berberidis), York, 23 June 2009

Adult berberis sawfly (Arge berberidis), York, 23 June 2009

Interestingly though, when I checked up on the larvae this lunch-time, they were gone!

Nibbled berberis leaf with no Berberis sawfly larvae left, York, 24 June 2009

Nibbled berberis leaf with no Berberis sawfly larvae left, York, 24 June 2009

So, looks like they have a predator.

I asked Andrew Halstead of the Royal Horticultural Society what he thought had happened to the larvae, and he replied:

‘I don’t know what happened to the missing larvae.  Sawfly larvae that feed in exposed positions on the foliage, such as those of berberis sawfly, ought to be easy targets for birds. However, they evidently survive in large numbers, which indicates that there are no effective predators.  Some other caterpillars, such as those of the mullein moth and large cabbage white butterfly also feed in exposed positions on their host plants with apparent impunity. All of these larvae have prominent yellow blotches on their bodies, which may be a warning sign that they don’t taste good.’

So, I’ll have to keep a very beady eye out and see if I can spot any birds eating the next larvae that hatch.

Meanwhile, if you see Berberis sawflies – adults or larvae – in your garden, the Royal Horticultural Society would like to know about it. You can record your sighting with them here.

Find out more about Berberis sawflies (including photos of eggs, larvae and adults) here.

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