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predators

140519-0621

We have not seen much dew in the Bay Area in this year of record drought, so here’s a reminder that sometimes there is actual moisture around here! On December 24, 2012 the sun lit up this tiny spider web among irises and Santa Barbara daisies.

140519-0623The spider that spun this web was no larger than a pin head, yet it contained enough instinctive knowledge to construct this complicated, 3-dimensional structure suspended expertly from  leaves and stems.

A typical organic garden contains thousands of spiders of many kinds. Most of them remain hidden in the vegetation, actively exploring for prey. Only a few spin webs that are large enough to be easily noticed.

The presence of spiders in the garden is ecologically profound, because they eat a significant fraction of the flying and crawling insects. In webs just like this one in the same garden, I have spotted fungus gnats, parasitic wasps, fruit flies, many other small insects, and even a lady beetle.

There are more than 42,000 kinds of spiders. They have been around for 400 million years, evolving from fascinating little critters called trigonotarbids that looked a little like modern ticks and mites.

Back in those early days there were no dew-spangled spider webs because web-weaving spiders had not yet evolved. True spiders with spinnerets appeared around 300 million years ago during the Carboniferous, a time when yard-long dragonflies cruised the skies. It must have been a great time to evolve predators!

There’s more about spider evolution at Wikipedia. There’s also a neat article about trigonotarbids.

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140405-0646

I love starting work in a garden early in the morning. One nice thing about these cool early hours is that many insects are still slow-moving and partly asleep. One such was this lacewing, a voracious predator of aphids and other small critters. I spotted it just as the sun touched the roses.

This one is probably a brown lacewing in the family Hemerobiidae of the order Neuroptera. These are less common than the green ones, and like the green lacewings they are always a welcome sight in the garden.

If the wide, stuffed-looking abdomen is any guide, this one is a female ready to lay eggs. The eggs are fascinating, deposited on the ends of erect, silk hairs attached to the undersides of leaves. Why the hairs? Some theorize that they protect the tiny, active larvae from each other by making it impossible for them to eat the other eggs before they crawl away looking for prey. Amazing little insects!

Here’s more about brown lacewings.

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The lacewing was not the only critter hiding among the roses.

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