Yeah I realy have no problems (other than what other people have) in getting silk to drop from crawlers. It just seem to be random with with a lvl 15 thf sub, and a lvl 35 main. I tried klling crawlers in the maze at about lvl 30 thinking that these may give me better drops because they are higher lvl and still have me xp but no luck.
I can kill crawlers all day in E/W saruta my best is like 6 silks in less than 30mins while actauly hunting for beads from birds.