Bowl and Doily Weaver
Frontinella communis
Camp Creek, Maricopa Co., Arizona, USA. 22 March 2015. Not including the legs, this female is about 4mm long.
Linyphiidae -- Sheet-weaver Spider Family
Spiders are capable of long distance movement when they are small spiderlings. They accomplish this with strands of silk that function like kites in the wind. The bowl and doily spider frequently engages in this 'ballooning' which might help explain its continent-wide distribution. Bowl and Doily Weavers are mostly found during the spring months in the Sonoran Desert.