• View of Half Dome and Washington Column in Yosemite Valley

    Yosemite

    National Park California

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Wildlife and Other Sightings: Golden Digger Wasps & Feathers

August 04, 2012 Posted by: BW - Mather District Volunteer Interpretive Ranger

Golden Digger Wasp
Sphex ichneumoneus
   
Golden Digger Wasp burrowing  Golden Digger Wasp with prey

July 29, 2012
Big Oak Flat Information Station

Golden Digger Wasps are invading Big Oak Flat!  Don't be alarmed, these beneficial insects are not aggressive and will not bother you unless provoked. A colony of several dozen burrows was discovered in the Big Oak Flat Information Station parking lot median. These fascinating wasps could be seen actively digging, bringing a tiny ball of sand to the surface and spreading it out in a patchwork of tan over the grey gravel median. The Golden Digger Wasp is a gorgeous and colorful insect with golden hairs decorating its black head and thorax. A black tip caps its red-orange abdomen and matching legs. As deadly (to other insects) as they are beautiful, it didn't take long before these wasps were observed bringing prey to their nests. Wasp venom is designed to paralyze other insects and these wasps hunt crickets or grasshoppers. They bring the immobilized prey back to the nest to supply their larva with food. The larva will spend the winter in the burrow, emerging next summer to repeat the cycle. For being such an efficient predator, the adult wasp is actually a vegetarian, feeding only on flower nectars and other plant fluids. Not only do these wasps help control pest insects, but they are pollinators too!

Feathers
  
Feathers on trail

August

Keep an eye out for feathers on the trail as the birds of Yosemite are replacing their flight feathers this time of year.  This process is called molting and it allows the birds to replace damaged or worn feathers. Although birds molt every year, not all feathers are replaced at once and some species take several years to replace their full set. This pattern of old and new feathers is a handy way for researchers to estimate the age of a bird. 


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Did You Know?

Nevada and Vernal Falls

In Yosemite Valley, dropping over 594-foot Nevada Fall and then 317-foot Vernal Fall, the Merced River creates what is known as the “Giant Staircase.” Such exemplary stair-step river morphology is characterized by a large variability in river movement and flow, from quiet pools to the dramatic drops of the waterfalls themselves.