Friday, September 28, 2012

Mystery solved

When I came home yesterday evening, I noticed that the fluffy, white insects were not limited to the backyard.  They were also drifting around in front of the house, as well as up and down the street.  I decided to make another effort to identify them.  I was able to scoop several out of the air with my hand, and I captured one in a glass jar for closer inspection.  Going through the insect key from the beginning, I found that what I had was a woolly aphid (Aphididae, subfamily Eriosomatinae). 

A woolly aphid migrating to a new host plant.  For scale: this aphid is about 3mm long.
These aphids alternate between feeding on alders and silver maples.  While on one host, they form dense colonies of wingless clones.  Then, when it is time to migrate to the next host, they produce winged offspring like the one pictured above.

Thursday, September 27, 2012

Unsolved mystery

Recently, I have been seeing many fuzzy, white things floating through the air in the backyard.  Most of these are seeds.  Their silky hairs help them catch the wind in order to disperse away from their parent plants.

A wind-dispersed seed caught against a rose leaf.
However, this evening, the air seemed to be full of a new kind of white speck.  These specks appeared to be flying, not simply drifting on the breeze.  I followed one until it landed on a leaf.  It was indeed an insect, not a seed.  Its fuzzy, white appearance came from a fringe of white tufts around its abdomen.

The mystery insect on a lilac (Syringa sp.) leaf.  It is very small!
A close-up of the mystery insect.  From its wings, it looks like a parasitic wasp.

As far as I can tell, the vein patterns on the wings suggest that it is a parasitic wasp.  Perhaps these insects had just emerged from a host somewhere in the garden, but I'll have to leave this as an unsolved mystery for now.

Tuesday, September 25, 2012

Nap time

Bees must be warm in order to fly efficiently; however, they are cold-blooded animals.  They can warm themselves by rapidly vibrating their flight muscles -- but this takes up a lot of energy.  What else can a bee do when it gets caught out in bad weather?  Like the bee pictured below, it can rest in a flower until it warms up again.

A bee resting in a hollyhock flower on a chilly morning.
Flowers are ideal spots for a nap on a chilly morning (as long as there isn't a predator lying in ambush).  Not only do flowers provide food and shelter, they can also be significantly warmer than the ambient air temperature.  Some flowers in cold climates even use heat as a reward for their pollinators.

Explore some more: Warm flowers, happy pollinators

Friday, September 21, 2012

You don't have to leave home

Last weekend, I tagged along on a field trip about regional geology.  The scenery was stunning to look at and it was nice to learn more about how it was formed, but my real goal was to see more insects and spiders.  

Palouse River Canyon.  It may look like Arizona, but it really is Washington.
One stop, along a river shore, was particularly impressive for its large number of extremely large spiders.  Some of these spiders made their funnel webs between the rocks by the water's edge, while others stretched their webs between the trees and bushes.

A large orb-weaver spider.
An orb-weaver spider eating a stinkbug.
I remember thinking at the time how the proximity to water must provide these spiders with lots of prey -- and how glad I was that I couldn't stumble across anything like that in my own backyard.  I returned to the bus with a bit of web stuck to my arm and an uncomfortable crawling sensation.

Yesterday, I got to experience that creepy-crawly feeling again, and this time in my own backyard.  I found a web strung between two hollyhocks, with something the size and color of a dried hollyhock seed pod hanging in the middle.  Only it wasn't a seed pod; it was the owner of the web.

On closer inspection, there is no way to mistake this orb-weaver for a hollyhock seed pod -- but it was about the same size.
I didn't like putting my camera -- and hands -- directly under this spider, but it was the safest way to look at the other side.
Although the spider looked menacing, it did not make a move while I photographed it.  The creepy-crawly feeling came later, when I turned back to look at the web again and the spider was gone.

Wednesday, September 19, 2012

The weevil within

The hollyhock seed pods are drying up now and rings of holes have become visible around many of them.  I was not surprised to see these holes, since in the past weeks I have seen many bugs feeding on the seed pods.  What did surprise me was that quite a few holes had something protruding out.

Something is sticking out of one of those holes in the hollyhock seed pod.
Intrigued, I began peeling open a pod.  Inside, in addition to the hollyhock seeds, I found a large group of hollyhock weevils (Apion longirostre).  Once exposed, the weevils quickly dispersed in search of cover.

A hollyhock seed pod full of hollyhock weevils (Apion longirostre).
How had all those weevils gotten inside the seed pod?  Through holes -- but not the holes in the seed pod.  There were matching holes in the seeds themselves, and not all these holes were empty.  Several had the long snouts and antennae of yet more weevils sticking out.  I broke open the seed pictured below to reveal the weevil that had grown inside.

A hollyhock weevil (Apion longirostre) developing inside a hollyhock seed.
Earlier this summer, a female hollyhock weevil must have laid her eggs in the ovaries of the flower.  As the seeds developed, so did the weevil larvae, consuming the seeds from within before pupating and finally emerging as adults.

Monday, September 17, 2012

Earning their stripes

Just over a month ago, I found the garden crawling with tiny, white spiderlings.  Since then, I have been observing their progress intently.  Many of the crab spiders have captured enough prey to increase several times in size (for example, compare the spider in this picture to the one below).

A juvenile crab spider waits for its next meal.
Others have changed in appearance, as well as in size.  These spiders now sport dark stripes on the head, abdomen, and forelimbs; they may be juvenile males approaching their adult coloration.

A juvenile crab spider (Thomisidae), most likely a male Misumena vatia.
One thing that hasn't changed is that there are still crab spiders nearly everywhere I look.  They are on plant stalks, leaves, seed pods, and - of course - flowers.  However, space on flowers is limited.  Crab spiders attempting to take up residence on a new flower may find themselves too close to a hungry neighbor.

Two crab spiders face off on a flower.

Friday, September 14, 2012

The seed defenders

Many seed predators have converged upon the hollyhocks and are feasting on the seeds.  Nevertheless, things may not be as bad as they first appear for this new generation of hollyhocks -- for the seed predators have been attracting enemies of their own.  During my rounds through the garden, I have noticed that the hollyhock seed pods are also routinely patrolled by a number of predators.  The most common of these predators are wasps and ladybugs.

A European paper wasp (Polistes dominula) on a hollyhock seed pod.
A ladybird beetle (Coccinellidae) inside a hollyhock seed pod.
Although many of the hollyhock seed predators that I have seen are bugs, not all of the bugs on hollyhocks are necessarily there to eat seeds.  When I first saw the bug pictured below, I thought it was piercing through the pod to reach the seeds inside.

A bug eating a much smaller insect, speared on its mouthparts.
Upon close inspection, however, a very small insect is visible at the end of the bug's mouthparts.  In contrast, the bug pictured below was no longer a predator of any kind.  Instead, it had become the prey of a crab spider.

A crab spider (Mecaphesa sp.) eating a bug on a hollyhock seed pod.

Thursday, September 13, 2012

We only come out at night

Recently, I have been seeing less and less green in the garden.  The weather has been very dry and is now getting cooler -- but these aren't the only problems that the plants have been facing.  They are also losing large portions of their leaves to hungry herbivores.

A rose leaf that has been damaged by an insect, possibly a leafcutting bee.
I wanted to know what was altering the leaves, often in quite interesting and aesthetically pleasing ways; however, during the day, the "artists" remained anonymous.  Searching again after dark, I found a very different garden.  Wherever I looked, there were earwigs (Forficula auricularia).  I may have seen over a hundred earwigs during a single tour of the garden -- and wherever I saw them, they were eating.

A European earwig (Forficula auricularia) eating the edge of a leaf.
Although by far the most numerous, the earwigs were not the only insects busy chewing up leaves.  I also found a couple of black vine weevils (Otiorhynchus sulcatus) feeding under the cover of darkness.

A black vine weevil (Otiorhynchus sulcatus) eating the edge of a leaf.
The weevil above was just getting started on its leaf when I found it.  It was startled by the camera and dropped to the ground (these weevils cannot fly).  However, other leaves nearby had not been so lucky.

Tuesday, September 11, 2012

Please stop bugging my plants

Just a few hollyhock flowers, at the very tops of the stalks, are still blooming.  Only occasionally does a bee come to visit one of these flowers.  This is a vast change from earlier in the summer, when the flowers were abuzz with a frenzy of pollinator activity.  Proof of this past pollinator attendance remains further down the stem, in the form of pods packed with seeds. 

A ring of hollyhock (Alcea rosea) seeds is visible within the seed pod.
The multitude of seeds has made me hopeful that next year we could have many more hollyhocks growing in the garden.  Unfortunately, hordes of insects have another plan for these seeds: dinner.

A stink bug (Pentatomidae) feeding on hollyhock (Alcea rosea) seeds.
Among the worst offenders are several species of true bugs.  These bugs sit on the outside of the seed pods and pierce both the outer wall and the seeds with their long, straw-like mouthparts.

A seed bug feeding on hollyhock (Alcea rosea) seeds.

Since the bugs are feeding on seeds before they have completed developing, I can't even harvest them to keep them safe.  I just hope that some seeds will survive this gauntlet of seed predation.

An immature bug feeding on hollyhock (Alcea rosea) seeds.

Friday, September 7, 2012

Peekaboo, I see you!

From my previous posts, you may have guessed that crab spiders (Thomisidae) are my favorite spiders.  However, I have not been posting much about my second favorite spiders: the jumping spiders (Salticidae).  

A jumping spider on a hollyhock stem.
Most of the time, as I approach a crab spider it will just sit still on a flower, or even sidle underneath the flower to hide.  In comparison, jumping spiders are much more interactive.  Although they may initially go into hiding, they frequently will peek back out and watch me with their large eyes.

A jumping spider watches me from behind a rose hip.
The spider in the picture below was especially bold.  It watched as I wiggled my finger back and forth in front of it.  Knowing that they are good jumpers, I had tried to keep my finger a safe distance away.  Nevertheless, before I knew it, the spider had disappeared from the post and reappeared on my finger.  Instinctively, I shook my hand, and the spider landed back on the post.

A jumping spider briefly watches my finger before jumping onto it.
If you would like to watch a jumping spider watching you (without the danger of it jumping on you), take a look at the video below.

* To see this video in high definition (1080p), you may need to (1) click "YouTube" to watch on the YouTube website and (2) change the settings at the bottom of the video screen.

Wednesday, September 5, 2012

Surprise inside

Earlier in the year, the crabapple (Malus sp.) tree in the backyard was buzzing with bees.  Now, it is covered in small, sour fruits.  I keep checking the fruits to see if anything will eat them, but so far they have been left alone.  Instead, I have noticed that many of the crabapple leaves are getting rolled up and eaten.
A rolled crabapple (Malus sp.) leaf.
Curious to know what was inside, I began carefully unrolling the leaves.  Within the first few leaves I found white silk, insect frass (the black droppings in the picture below), and ladybugs.

A convergent ladybug (Hippodamia convergens) in a rolled crabapple leaf.
However, most ladybugs are predators, not herbivores.  Something else must have been rolling and eating the leaves -- and then been eaten by the ladybugs.  I kept looking.  On about the fifth leaf, I finally found a leaf roller caterpillar.

A leaf roller caterpillar inside a crabapple leaf.
Having found only harmless (to me) insects inside the leaves, I started unrolling the other leaves with less caution.  However, I soon discovered that the leaf roller caterpillars were not the only ones rolling leaves.  As I peeled open another leaf, I saw long, spindly legs -- and I immediately released the leaf.  I brought a flashlight down to the garden so that I could peek inside through the narrow opening without further disturbing the leaf.  With the aid of the flashlight, I found that the legs belonged to a spider guarding its egg sac.

A spider and egg sac inside a rolled crabapple leaf.

Tuesday, September 4, 2012

No hitchhiking!

Some insects work hard for a living, whereas others try to get a free ride.  In the picture below, a beetle hitchhikes on the antenna of a foraging bumble bee.

A beetle (Antherophagus sp.) gets a ride on the antenna of a bumble bee (Bombus ternarius).
This bumble bee spent some time trying to dislodge the beetle, but the beetle did not loosen its grip.  Eventually, the bee flew off with the beetle still hanging from its antenna.

The bumble bee attempts to free itself from the beetle.
The adults of these beetles feed on flowers; hence the genus is suitably named Antherophagus ("flower-eaters").  However, the beetle larvae feed on debris within bumble bee nests.  To get from one feeding site to another,  the beetles simply catch a ride on a passing bumble bee forager.

An Antherophagus beetle feeds on a hydrangea flower.