Tuesday, 24 July 2012

Move over, bees....

...the hoverflies are coming!

As the summer rolls on, the hoverflies are really making their presence felt - where earlier we saw plenty of Nomada and Andrena bees, we are now seeing a definite shift towards bumblebees and hoverflies as the most abundant pollinators.  In all habitats, hoverflies are floating around, some of them easily overlooked for being so small and slight - others, seen, but too zippy to catch with the camera!

Hoverfly (Episyrphus balteatus) on California poppy (Eschscholzia californica)

Hoverfly cruising over courgette flower

We were out this morning, checking on progress of some of our nectar-rich flower beds around Leeds.  At Armley, the poppies were spectacular...

Poppies at Armley Park
...and the bed was buzzing with highly energetic bumblebees - some of them buzzing with such vigour, that they were knocking the petals off the poppies!  Just across the park, a flower bed planted with more conventional bedding plants (African marigolds, petunias, bushy lobelia) was noticeably quieter; fewer bumblebees, but there was an impression of more hoverflies being around.  The usefulness of such flowers as petunias for pollinators is often doubted, and though we did see them being visited by a few white-tailed bumblebees obviously seeking nectar, it was the activity of some of the hoverflies that proved most interesting: some appeared to be laying eggs in the upper side of petunia leaves, leading me to wonder whether the petunias were offering something particularly useful in terms of oviposition sites.

Hoverfly - egg-laying, or something else?

 I was surprised that anything would choose to lay eggs on the upper side of a leaf, especially at this time of year, as eggs and developing young would be at increased risk of dessication and sunburn - most insects choose to lay on the underside of leaves, to maintain a more stable environment, and to protect against predation.  It may be that the small white capsule seen being deposited was of a more scatological nature than an egg - we shall follow this up, when we get a minute! 


  1. Nice pictures :-). We start to see more hoverflies as well now which is nice. Looking forward to the sampling next week after all the weeding this week.
    Interesting what the hoverfly did on the leaf, if it was really lying eggs. Were there a lot of aphids on the plant or nearby?

  2. Yes, I had a quick look, but there didn't seem to be more than a smattering of aphids on the petunias, which, along with the location, made me wonder about my initial interpretation. While we were there, we saw at least two other occasions of this laying of a white pellet on the topside of the leaf, plus I've observed it also on beech leaves, so it's definitely a widespread behaviour - just haven't yet figured exactly what is going on yet! Any thought, queries, observations, always welcome :) I guess the question is, do hoverflies poo?