Friday, August 30, 2013

A dirty job

On the same excursion during which I encountered the strangely attractive crab spider, a fellow walker called my attention to a wasp that was on the path.

A mason wasp (Eumeninae) collecting mud from the ground.
The ground was still moist from rain in the previous days and the wasp appeared to be digging in the mud with its mandibles.  Then, as I was pressing the shutter button of my camera, the wasp suddenly took flight.  By chance, the wasp and the mud ball it was flying off with were caught in the picture.

The mason wasp flies off with the mud ball held in its mouth.
What could a wasp do with mud?  It could build the walls of a nest!  I had seen similar wasps around the house which had done just that.  The wasps had constructed their mud nests in crevices and had progressed to provisioning the nests with food.  In the picture below, you can see a mason wasp's nest in the frame of one of our windows.  Just inside the entrance to the nest, part of a green caterpillar (a.k.a. food for the wasp's offspring) is still visible.

The nest of another wasp, complete with a green caterpillar to feed the wasp's offspring.

Wednesday, August 28, 2013

Keeping the enemy closer

While I was out for a walk, I came across a spider that was even more notable for abstaining from eating flies than the jumping spiders on the roses had been.  This spider had flies walking all over it, yet it made no move to catch them.

Flies sitting on a crab spider as it waits in ambush.
The flies were not in blind spots (crab spiders have eyes facing forwards, sideways and backwards); nevertheless, they may have been in the safest spot around.  Though the flies were tantalizing close, the spider may not have been able to reach around to grab them.  Another possibility could have been that the spider was simply waiting for larger or more appetizing prey to come along.

A bigger prey is a better prey?
However, as I was quickly being left behind by the rest of my group, after watching for only a little while longer, I left the spider to its hunting and the flies to their death defying stunts.

Monday, August 26, 2013

From a cradle to a grave

When the rose hip flies lay their eggs, they appear quite vulnerable.  The flies that I watched spent more than a minute with their ovipositors embedded in the rose hips.  If a predator was lurking nearby, it seems that the flies would have trouble escaping in time -- and, indeed, the rose hips are crawling with predators.

A jumping spider (probably an Eris species) sitting on a rose hip.
I can usually find jumping spiders on the rose plants and often on the rose hips themselves.  However, despite the apparently easy targets presented by the rose hip flies, I have not seen any being consumed by the jumping spiders.  Instead, I came across one of the jumping spiders with what I consider to be a much trickier prey item: another spider!

A cobweb spider (Enoplognatha ovata) being eaten by a jumping spider on a rose hip.

Friday, August 9, 2013

A cradle of roses

As the rose hips ripen here in Maine, they are acquiring both a pretty red blush and quite a few pockmarks.  What has been causing these small scars on the surfaces of the rose hips?

A ripening rose hip with several small, dark wounds.
In the past, I had often seen rose hip flies (Rhagoletis basiola) sitting on and nearby the rose hips.  These flies did not seem to be doing much, though, except sometimes rotating their wings in what may be a mating display.  However, over the last few days, I have caught a couple of the flies in the act --

A rose hip fly (Rhagoletis basiola) ovipositing into a rose hip.
 -- puncturing the rose hips with their ovipositors and laying their eggs inside.

Another rose hip fly (Rhagoletis basiola) ovipositing into a rose hip.
When I waited for one of the flies to finish laying and leave, I saw a fresh hole in the rose hip.  Checking back the next day, I found that the hole had scarred over to match the many other pockmarks on the rose hip.

Monday, August 5, 2013

Same time, same place, next year

Last summer, we found two song sparrow (Melospiza melodia) nests in the bushes in our yard in Maine.  When I returned to visit this year, the song sparrows were once again conspicuous in the garden -- especially around one of the bushes that had sheltered a nest last year.  Any time I came near the bush, at least one adult sparrow would appear nearby and begin calling loudly.  While trying to keep enough distance to avoid spooking the sparrows, I caught a glimpse of one of the chicks before it hopped back between the dense branches.

A fledgling song sparrow (Melospiza melodia) sitting in a bush.
A few days later, after it seemed the chicks had fledged, I went back to search more thoroughly for the nest.  It did not take long to locate last year's nest again; however, that nest was full of fallen leaves and appeared disused.  A new nest must have been concealed somewhere even deeper within the bush.  In contrast, I found that eastern phoebes (Sayornis phoebe) had been reusing the same nest as last year, with another four chicks successfully fledged this year.

Friday, August 2, 2013

A farewell to spiders

Although I was excited to find so many crab spiders in the backyard upon my return from Europe, I knew that I would not have the opportunity to observe them for very long.  As soon as I had unpacked my luggage, it was time to start packing again -- only this time, everything was going into a moving trailer headed for Texas.  Therefore, I filled many of my breaks from packing with surveys of the garden, which turned up tiny crab spiders...

A very small crab spider on an aster
...camouflaged crab spiders...

A juvenile crab spider on a shrubby cinquefoil (Dasiphora fruticosa) flower.
 ...and hidden crab spiders...

A crab spider concealed in a daisy inflorescence. well as the more obvious ones.

A female Misumena vatia spider sitting on a cornflower (Centaurea sp.).
Just as it seemed that packing would never end, the trailer was gone, my car was loaded for my drive down to Texas, and it was time to leave the spiders behind.