What is this insect that has invaded my home in Texas?
Myodocha serripes

http://www.americaninsects.net/ht/myodocha-serripes.html

Nice picture! Generally, the body plan of this guy indicates Hemiptera (the 'true' bugs), but the long neck is a bit strange, so a google image search for "Hemiptera + long neck' brought up this strong candidate. It looks like it's distributed in Texas, and is in fact, named for that distinctive neck: "The Long-Necked Seed Bug".

See also the BugGuide.net page for Myodocha