Note: this entry was rewritten on Sept. 23, 2008 due to a misidentification. Thanks to David (see comments below) for the correct ID.
Broad-flowered or hollyleaf gilia is an annual plant. A California endemic, it is found in the southern portion of the state in the southwestern Mojave Desert and adjacent foothills. These photographs were taken while I was developing the worst sunburn of my life in late March. This was thanks in part to the cool winds that gust through the Antelope Valley from the nearby mountains in spring, which deceived me into believing I wasn’t being slowly roasted by the sun.
The closely-related species (and the name of my original, incorrect identification) Gilia tricolor is a popular annual ornamental, if search engine results are any indication. For a comparison between the correct identification and my original misidentification, Calphotos provides an extensive set of photographs of both Gilia latiflora subsp. davyi and Gilia tricolor.
As for the insect in today’s photograph, I believe it is Hyles lineata (source: Butterflies and Moths of North America Database), or the white-lined sphinx. Wikipedia has some photographs of the larvae (caterpillars), as does this site. While many moths are nocturnal, it is noted that the white-lined sphinx will often be active during the day (and this one was plenty active!). I think I’ve linked to it before, but if you haven’t seen the US Forest Service’s site on Celebrating Wildflowers, it is worth investigating. They even have a section on moth pollination.