Friday, June 29, 2012

The day my flower fell apart

You might expect that a crab spider has an easy life.  After all, it should be able to sit back on its flower and relax, basking in the sun, until its food delivers itself.  However, for the young crab spider featured in this video, just staying on the flower is a struggle. 

Wednesday, June 27, 2012

Be careful when you stop to smell the roses

The wild roses are in full bloom and they are my first stop on each trip to the backyard.  As soon as I step out the door, I am greeted by their delicate and inviting fragrance.  However, I approach them hesitantly, scanning each blossom from a distance before stealthily drawing closer.  Although I have been caught by the thorns a few times in the past, my caution stems from a different source.

Many of the flowers harbor hungry predators waiting to pounce on their next meal.

A female crab spider (Misumena vatia) waits ready to grab its next meal with its raptorial forelimbs.
Of course, I am in no danger of ending up on the menu.  The predators are crab spiders; for them, even bumble bees are usually too large to handle.  The reason that I must move carefully is to avoid startling the spiders.  If I move too quickly or let my shadow fall over them, they may go into hiding underneath their flowers.

Instead of building webs, these spiders ambush their prey.  They have long forelimbs that they hold outstretched (resembling a crab's claws) until some unwary victim comes within reach.  Flowers are ideal hunting sites, since not only do they attract many insects, but also the insects are preoccupied with gathering food and may not notice the spider until it is too late.

As long as they are not disturbed, female crab spiders are unlikely to move much farther than to a neighboring flower.  This makes it possible to locate the same spider day after day.  But why take the trouble to look for something that sits nearly motionless for hours at a time?  By checking on a crab spider briefly each day, you can follow its progress as it tries out new hunting sites and strategies, changes color to match its current flower, consumes ever larger and more impressive prey, constructs a nest and guards its eggs.  If you are lucky (or set up a video camera), you may even chance upon the rare moment in which the spider moves with astonishing speed to grapple with its prey.

Therefore, even though these spiders will not harm you, you should be careful when you stop to smell the roses.

A male Misumena vatia eats a very small fly.

Monday, June 25, 2012

Introduction: Flowers and their many visitors

Everywhere I go, I love to stop and look at flowers -- or rather, at what is on flowers.  Flowers attract a multitude of visitors, including not only bees and butterflies, but also moths, wasps, ants, flies, beetles, bugs, spiders, mites, birds, bats and more.  Although we enjoy flowers for their sweet aromas and bright colors, in nature, flowers are the stage for desperate struggles for survival.  Many flower visitors are only making a quick stop for a drink of sugar-rich nectar, but others come seeking a refuge from bad weather or a nursery for their offspring.  Yet others are in search of mates or are waiting to ambush their prey.  As they travel from flower to flower, many visitors aid plant reproduction by transporting pollen; however, they may also bring diseases that will sterilize the plants they infect or parasites that will wait to catch a ride on the next visitor.  If you look closely, you are likely to see much more than just another pretty flower.

Fascinating events are unfolding every day, and they can be watched just outside, in the backyard.