Montmartre Elderberry

My attention was drawn by a great number of ladybeetles. Ladybeetles have something special amongst insects. I came nearer to observe them...

And I could discover that the young sprouts of the elderberry were covered by thick sleeves of aphids.
Those aphids are Aphis sambuci, the term sambuci coming from the latin name of the elderberrry, Sambucus nigra.

In front of that, I guessed that I could take some interesting pictures.
I first observed many different kinds of ladybeetles.

We have seven-spotted ladybeetles (Coccinella septempunctata), two-spotted ones (Adalia bipunctata, with two different colors ), a pink ladybeetle (Oenopia conglobata), a so-called asiatic or chinese ladybeetle (Harmonia axyridis), a yellow one, well hidden, and even a Scymnus sp..

Since there was plenty of food and since the spring was at least beginning, everybody was rather busy...

This female taking the time for a little snack...

In the mean time, the aphids were pretty active at work...

Some subjects appear with wings to go and settle on other trees. On the photo on the right, one can see a viviposition by two females (they lay a larva which already hatched from the egg in the the mother's abdomen.

The honeydew, as is well known, attracts ants. Some ant species even "grow" theirs aphids, protect them and can carry them to better places to pasture.
Here, we have Lasius emarginatus.

The honeydew produced by the aphids makes ants happy and gardeners unhappy, because of the damage to the tree leaves (which may foster the development of the black fumagin). It also attracts other visitors, like this Tachina fera, and many others.

Some of those visitors were happy with the honewdew, other associated feeding and reproduction, since I could soon observe the presence of hoverfly (Syrphids) eggs in the aphid colonies.

One could therefore expect the apparition of larvae, which are known to feed on aphids. Below, in particular, larvae of Epistrophe eligans.

And what did the ladybeetles, in the mean time? They laid eggs...

Normally, they lay eggs on the underside. Why did this one choose the upperside? Who knows...

On the other hand, I still lacked the dramatic pictures I was expecting. As a matter of fact, this picture is the only one where I saw a 7-spotted ladybeetle eating an aphid. Therefore, I did some search and found out that Aphis sambuci are "naturally" protected from some predators because they accumulate a toxic substance, sambunigrin, produced by the elderberry, which is a precursor of the cyanhydric acid.
See in particular this reference.

Sambunigrin is without effect on the two-spotted ladybeetles, as we already saw it above.

Some ladybeetle larvae appeared, but not in a huge number, if we consider the big number of adults and the (relatively lower) number of eggs. One may think that some eggs were eaten by some animals (ants? hoverflies? others yet?).

Even one day this larva of Scymnus sp.. This ladybeetle is frequently used against aphids in the agriculture and can now be found in many places.

Some of the visitors didn't came on the elderberry for the honeydew alone...
but were looking for larvae to lay their eggs (parasitic behavior).

For instance, this larva (probably Eupeodes sp.), normally straight, was regularily jolting (all 10 to 15 seconds) and bowing like in this picture, probably bitten by its parasitic host.

A few days later, the damages could not be overseen.

This series stops here. This elderberry was the center of an intense activity in April and in the first days of May, but returned to quietness since. The sleeves of Aphis sambuci are still there, together with the ants, but they are not stimulated anymore to produce honeydew. Maybe because the eldeberry began to produce flowers? Nitrogen contents?
On the other hand, all visitors we could observe in this period can be more interested in other plants (in particular many roses) and in their inhabitants.
One should add that if Aphis sambuci are abundant, they don't make a first choice diet for all species (they are even toxic for some ones). See for instance this page on ladybeetle feeding which states that this diet is not sufficient for the growth of some ladybeetle species.

While this series began on April the 11th in 2005, we had to wait for May the 12th to see the arrival of the aphids.

This Epistrophe eligans didn't wait long to lay its eggs. Below, we can alreday observe another syrphid larva amongts aphids.

Likewise, this female Paragus pecchiolii wanted to lay eggs amongts aphids.

However, while ants didn't anything agains the Epistrophe, they were really nervous against this one, which had to wait for an opportunity, hiding some distance away.

A few days after, one could see that it had succeeded.

The elderberry had this brief burst of activity, but this belongs now to the past. We will have to wait for next year...