Saturday, July 13, 2013

Of ladybugs and linden trees

The linden tree seems to be a little late this year. Or perhaps it's the aphids that are running behind schedule. It wasn't until this week that the tree started to wake up. And yesterday, I found the first ladybugs. Not the first to arrive, since some have pupated already, and at least one larva is in his last instar. Maybe they started in the top of the tree, where the sun shines almost all day.

On the leaves that I could reach, I found aphids producing honey, ants eating the honey, ladybug larvae eating the aphids, assorted wasps, including those bright orange ones, looking for a place to lay eggs, a very pretty fly all spiffed up in red eyes and blue back, who left when I touched his branch. And the adult ladybugs, supervising everything.

Aphids, full-grown, early instar, and an abandoned molted skin.

These are the  Eucallipterus tiliae, the Linden or Lime-tree Aphid. Their population will increase as the summer goes on, until every leaf has its little mob. The mature ones (see the photo above) feed on the thick veins of the leaf, where the sap flows freely. The youngsters, with much smaller feeding stylets, are restricted to the tender areas between veins.

They produce more honey than the ants can eat, so it "rains" onto the grass below the tree. The first year I noticed them, the grass was black with mould, growing on the honey. Since then, I've made sure to wash off the grass well every day or so; last year, there was no mould. None this year, so far, but we're in early days yet.

Adult, Harmonia axyridis, a 19-spotter with a mostly white pronotum. I love those shiny eyes!

Another adult, with smaller spots.

One of the ladybugs had a mostly black pronotum, although it was the same species; it had the "W" clearly marked on the front. I wanted his photo, but he was not in the mood. He ran, and I chased him, from one leaf to another, to the main branch, me getting stickier by the minute, he getting angrier, I think, because he finally dropped onto my arm. "Yay!", I thought, "Now I've got him where I can see him."

And then the little bug bit me, and flew away, muttering imprecations as he went.

The pupas don't run, and they don't bite.

The frills are the old larval skin, shed as he pupated, and glued to the leaf at his tail end. Silky threads hold him down. I'm wondering how he manages to anchor those threads, encased as he is. I'll have to watch another one pupate to see.

And I have no idea what this next thing is. It's too small, and the wrong shape, to be an abandoned ladybug pupa. There is no larval skin, and the ladybug splits her pupa down the back, leaving a black thing standing upright.

It looks as if there is a hole in the front end, where the adult insect emerged. Whether that was the original inhabitant, or a wasp that had parasitized it, I can't tell.

What is this?

Next: a weird fly in my kitchen.

1 comment:

  1. You so inspired me awhile ago. I love your macro photos and bugs.
    I love mine, too!
    Cheers from Cottage Country!


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