Quick! How long have insects inhabited this earth?

If you're taking a biology or an entomology course, you'll be asked that question on an exam. If you're attending the Entomological Society of America conference Nov. 16-20 in Reno, you probably already know that.

A good answer: 400 million years.

The world's oldest known insect fossil is 400 million years old. according to findings published Feb. 12, 2004 in the journal Nature.

The evidence: jaw fragments measuring less than one two-hundred-fiftieth of an inch across discovered in 1919 in chert (a partly translucent crystalline rock) in Rhynie, Scotland. Shortly after that, scientists moved the fragments to a drawer in the Natural History Museum in London.

Under high magnification, the miniscule fragments show sockets that form part of a "hingelike mechanism that clearly identifies them as mouth parts of a true insect," the New York Times wrote.

To think that insects existed at least 400 million years ago! Scientists earlier thought 300 million years ago. What's a few million years? Well, the fossil record suggests that insects were among the first animals to live on land. The first ancient animals to fly were undoubtedly insects (even before flying dinosaurs).

Scientists David Grimaldi, a curator of entomology at the American Museum of Natural History, New York, and Michael S. Engel, a paleoentomologist at the University of Kansas, said that when they first discovered the age of the fossil fragment they looked at each other and said "Holy moly!

It's been a long time since I've heard "Holy moly!" but then it's been a long time since insects have inhabited the earth.

Holy moly! 400 million years!

It's tough being a drone honey bee this time of year.

The drones, or male bees, don't survive the winter.

Bee breeder-geneticist Susan Cobey of the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis  admits to having a soft spot for drones. Once the honey-gathering season is over, the worker bees (sterile females) evict the drones from the hive, as the only function of the males is to mate. 

 “They're cold and hungry, sitting there on the doorstep and wanting to go back in. They're attacked and they die.  Well, it's a matriarchal society.”

Throughout the spring, summer and early fall, drones routinely leave the hive in mid-afternoon on a mating expedition.  Last Friday at the Laidlaw facility, the drones exited the hives around 3 p.m.  They wobbled out of the hive and then took off. The plan? Head  for "the drone congregration area,"  said UC Davis apiculturist Eric Mussen.  Drones congregate not far from the hive and wait for a virgin queen bee to arrive. 

The virgin queen mates with mulitple drones, often as many as 12 to 25, and then returns to her hive to lay eggs for the rest of her life. She never leaves the hive after her maiden flight. "She's an egg-laying machine," as Cobey says.

For the drones, it's a different story. They mate and then they die. And if they can't find a mate? With the onset of cold weather and winter, if they try to return to the hive, their sisters won't let them back in. They don't want the drones taxing their food supply.

Oh, brother, where art thou? 

Ever wonder why the stink bug stinks?

The stink bug, from the family Pentamodae, is a shield-shaped insect that tomato growers would love to ban from the face of this earth.

Some 50 species exist in California. The adults are either brown or green. Most stink bugs are plant feeders. However, the species of one subfamily prey on other insects, according to the excellent guidebook, California Insects, written by Jerry A. Powell and Charles L. Hogue  and published by the University of California Press.

When a group of us from the UC Davis Department of Entomology worked the soil today at the Harry H. Laidlaw Jr. Honey Bee Research Facility, west of the central UC Davis campus, we encountered several lizards, lots of centipedes and ladybeetles, and several stink bugs.

So, how did the stink bug get its name?  It stinks when it's  disturbed.  It emits a powerful odor from its thoracic glands to ward off predators.

The stink bugs we unearthed didn't stink. Guess we didn't disturb them enough!

Okay, everybody in the pool!

That means bees, too?

It does.  Sweat bees.

You may have noticed the tiny bees--common name “sweat bees” from the family Halictidae--in your swimming pool or pollinating your flowers.

They're attracted to perspiring skin (thus the name “sweat bees”). Sometimes when you're splashing around in the pool, you'll feel a sharp but harmless sting.

UC Davis emeritus professor Robbin Thorp, who researches native pollinators, identified this one (below) as a Lasioglossum  (Dialictus) sp. female. 

A dull metallic gray, brown or blackish in color, they're found throughout California. They nest in ground burrows.  

If you want an excellent book on providing native habitat for these native bees,  you'll want to obtain a copy of Farming for Bees: Guidelines for Providing Native Bee Habitat on Farms, written by Mace Vaughan, Matthew Shepherd, Claire Kremen and Scott Hoffman Black and published by the Xerces Society for Invertebrate Conservation, an international, nonprofit, member-supported organization dedicated to preserving wildlife habitat through the conservation of invertebrates.  For more information, contact the Xerces Society  4828 SE Hawthorne Blvd., Portland, Ore. 92715 or access the Xerces Web site.

They write: "North America is home to about 4000 species of native bees, most of which go overlooked. These insects are not the familiar European honey bee, nor are they wasps or other aggressive stinging insects."

With the decline of honey bees, expect to see more reliance on native bees.

Excerpts from Farming for Bees:

• If enough natural habitat is close by, native bees can provide all of the pollination necessary for many crops
• Fifty-one species of native bees have been observed visiting watermelon, sunflower or tomato in California
• Native pollinators have been shown to nearly triple the production of cherry tomatoes in California