Friday, June 28, 2013

March of the larvae, continued

The masses of beetle larvae were not the first to infest the grey alders (Alnus incana) this year.  Nearly as soon as the leaves had appeared in April, large numbers of bluish black beetles appeared on them.

Alder leaf beetles (Agelastica alni) feeding on grey alder (Alnus incana) leaves in April.
These alder leaf beetles (Agelastica alni) spent their time consuming large portions of the leaves -- and mating.

Alder leaf beetles mating.
By mid May, some of the female beetles had eaten so much that their elytra (wing covers) no longer fit over their abdomens.

A female alder leaf beetle in May.
These greatly enlarged females must have then gone on to lay numerous eggs, producing the legions of larvae that would be responsible for even more damage to the grey alder leaves.

Monday, June 17, 2013

March of the larvae

Although I encountered one moth larva crossing the sidewalk, the hundreds of other insect larvae that I have seen recently have been (not very surprisingly) on leaves.  What is surprising is that nearly all those larvae have been on the same few leaves. 

A group of alder leaf beetle (Agelastica alni) larvae eating a grey alder (Alnus incana) leaf.
These unfortunate leaves belonged to grey alders (Alnus incana) and hosted groups of 20+ beetle larvae.  The larvae not only shared the leaves, but also kept in tight formations as they ate their way across the leaves...

The beetle larvae on another leaf leaving a sinuous trail.
...leaving behind them trails of small holes.  However, some of the grey alder leaves were riddled with considerably larger holes.  To be continued...

Monday, June 10, 2013

The better to smell you with

As I walked through one of the small parks in my neighborhood, I noticed a small moth flying along the path.  Holding my breath, I hoped fervently that it would land somewhere nearby.  Why did I care so much about getting a better look at a little moth?  The answer is that I had never seen one like it -- and that it had seemingly impossibly long antennae.

A male fairy longhorn moth (Nemophora sp.).
Luckily for me, the moth did land right beside the path.  Approaching cautiously, I was surprised to see that it had stunning wings, with iridescent yellow, blue and purple markings and a fuzzy fringe.  I was still more impressed by the antennae, though, which were so long that they had made the moth's flight appear somewhat awkward.

Another view of the fairy longhorn moth (Nemophora sp.).
Moths use their antennae for smelling.  They can use their acute sense of smell to locate nectar to drink, host plants where they can lay their eggs, and mates.  Although both male and female fairy longhorn moths (Adelidae) have long antennae, those of the males are significantly longer and can be several times the length of their wings.  The males may use their long antennae to detect pheromones released by the females, or perhaps to locate other males, since male fairy longhorn moths are known to swarm in large groups.

Yet another view of this amazing little moth.

Friday, June 7, 2013

A sticky situation

Recently, my neighborhood has been filled with profusions of pink and white -- the rhododendrons are blooming.  Whenever it hasn't been raining, wasps and bees have been flying among the flowers, collecting nectar and pollen.

A bumble bee (Bombus sp.) hovers in front of a rhododendron flower.
The flowers have also been attracting ants, and in great numbers.  Many of the flowers have several ants busily gathering nectar even when the rain keeps other flower visitors away.  However, unlike the wasps and bees, the ants do not contribute to pollination of the flowers.

Ants gathering nectar in a rhododendron flower.
As I observed the ants, I noticed that the white rhododendron outside my building had an abundance of dead ants on its flower stems in addition to the live ants in the flowers.

One of the many dead ants on the white rhododendron flower stems.
At first, I thought there must be a predator roaming the rhododendron and taking advantage of the plentiful supply of ants.  I inspected the stems, but could not find any sign of a predator.  Instead, I found an ant that was in a different sort of trouble.

An ant at the base of a rhododendron flower.
Its legs had become trapped.  They seemed to be entangled in the fine hairs of the flower stem, which may also have been sticky.  Despite the ant's struggles, it was unable to free itself and eventually expired without making any further progress down the stem.

The ant trying to free itself from the flower stem.
Although I have not found a description of sticky flower stems in rhododendrons, it has been suggested that such stems can help keep nectar robbers and thieves (such as ants) out of the flowers of other plant species, thereby reserving the nectar for pollinators.

Monday, June 3, 2013

Ladies in waiting

A little over two weeks ago, I found a cluster of bright yellow eggs underneath a linden (Tilia sp.) leaf.

A cluster of lady beetle eggs on the underside of a linden leaf.
Although I did not need to wait for the eggs to hatch to know what was inside -- developing lady beetle larvae -- I hoped to see the larvae before they dispersed.  Therefore, I made a mental note of where the leaf was and occasionally checked on the eggs.  Finally, after two weeks, there was a change.

The lady beetles shortly after hatching.
The lady beetle larvae had emerged from their eggs.  Soon, they would spread out in search of food.  Checking the surrounding leaves, I saw that the lady beetle larvae would not have to go far to find a plentiful supply of aphids.  However, they would have competitors, as more batches of lady beetle larvae were hatching nearby.

A linden aphid (Eucallipterus tiliae) on a nearby leaf.