Color-coded for freshness

Many of the streets here in Berlin are lined with large horse chestnut (Aesculus spp.) trees, and for the last few weeks, these trees have been adorned by large clusters of flowers, or "candles".  Some of the trees have white flowers with yellow, orange, or dark pink markings...

A "candle" of horse chestnut (Aesculus hippocastanum) flowers.

... while other trees have pink flowers with the same yellow, orange, or dark pink markings.

A "candle" of red horse chestnut (Aesculus × carnea) flowers.

Meanwhile, the sidewalks beneath the trees have become littered with white and pink flowers.  Interestingly, though, all the fallen flowers have dark pink markings.  A closer look at the flowers still on the trees reveals that those with yellow markings have fresher petals and anthers (the structures that hold the pollen).

New flowers have yellow markings, which then turn orange and pink as the flowers age.

It is also only those young flowers that produce nectar to reward pollinators.  Thus, the different color markings enable visitors such as bees to quickly discriminate between rewarding and unrewarding flowers.  Nevertheless, the older flowers may help attract bees and other potential pollinators from a distance by contributing to the overall size of the floral display.

More than meets the eye

As I was on my way to the grocery store, I noticed that I shared the sidewalk with a much slower walker... one that was just inching along.

A geometrid caterpillar (Geometridae) inching its way across the sidewalk.

I crouched down to watch this geometrid caterpillar, more commonly known as an inchworm, as it crossed the sidewalk.  However, other pedestrians, who seemed intent on ignoring both me and whatever I was looking at, nearly stepped on the caterpillar.  Therefore, I decided to aid the caterpillar in its journey and gingerly picked it up.  Suddenly, something unexpected happened: the caterpillar went rigid and transformed into a twig.

The same caterpillar doing an impressive imitation of a twig.

Or, at least, the caterpillar took on the appearance and texture of a twig -- which might have been very helpful for the caterpillar had I been a bird looking for its next meal.

Ants in my pants, continued

Before I was chased away by the wood ants, I caught a glimpse of something metallic and blue pushing up through the sand about a foot away from the stump where the ants had their nest.

Something begins to emerge from the burrow.

This neighbor of the ants was a dor beetle (a.k.a. an earth-boring dung beetle).  Nearly as soon as the beetle had breached the surface, wood ants came running up to inspect their neighbor.

A wood ant (Formica sp.) inspects the dor beetle (Geotrupidae).

Although I thought that the ants might attack the beetle, each one ran off again after a short pause.

Another ant comes and inspects the beetle.

Then, once the beetle had finally emerged from its burrow, it simply turned around and backed down the hole again. 

The beetle safe (?) in its burrow.

Meanwhile, some of the ants were taking more interest in me than they had in the beetle, and so it was time for me to move on.

Ants in my pants

Unlike the ant-hills between the cracks in the sidewalk, the ant-hills that I came across in a nearby park presented real obstacles -- due to their size, the number of ants defending them, and the logs that had been placed around them. 

A wood ant (Formica sp.) nest.

Disregarding the implicit warning of the log barrier, I came closer for a better look at the ants.  The ants were swarming in and out of crevices in the stump where the colony had made its nest. 

A close-up of the wood ants.

Although not quite as apparent in the top picture, the ants had also spread out over the logs and throughout the surrounding area (including where I was standing).  Some of the ants, such as the one pictured below, were returning with captured prey.

A wood ant carries its prey back to the nest.

Meanwhile, a few others were crawling over my shoes, and at least one made it into the leg of my pants before I decided it was time to continue my walk.

Natural Current Microevents

Of the thousands of photographs that I take, only a few become featured on this blog.  However, now you can see some of the "microevents" that did not make it into larger narratives, along with other updates, at the new Facebook page for Natural Current Events!

A maple seedling just coming out from under the wing.

Spring cleaning, continued

In between some of the sidewalk cobbles, I found sand piles that were mountains compared to the ant-hills.  There were no ants around these sand piles, nor could I see anything inside when I peered directly down the large, round entrances.  However, as I explored a nearby forested park, I came to the top of a (real) hill that was littered with similar sand piles.

One of the many nests on the hill.

Here, the holes were not all empty.  As I walked along the path, I noticed a quick movement as something disappeared down one of the tunnels.  I crouched nearby and waited -- and after a moment a fuzzy head re-emerged.

A fuzzy head peeks out of the nest.

The occupant of the nest was a mining bee.  Unlike some other bee species (such as honey bees and bumble bees), mining bees are not social.  Each female has her own nest that she provisions with food for her offspring.  Nevertheless, these bees often nest in close proximity to each other.

Two of the mining bees crawling out of their holes.

The two bees pictured above seemed to live too close for their comfort.  Repeatedly, they would crawl forward to inspect each other, then rapidly retreat back into their nests before returning to the surface for another round.