Another poster mentions fabric forced such as 70 denier nylon used for the Hennessy UL line. It isn't so much the fabric thickness as the tightness of the weave. The Hennessy Hyperlights and Deep Jungles, for example use 30 denier nylon with a Spectra grid. Thinner and lighter fabric than the 70 denier used in the UL models. Both offer far better bite protection than the rather open weave fabrics used for the Deluxe models. Personally, I spray all my hammock bodies, packs, sleeping bags, and clothing with Permethrin. Of course, I'm in MA where we have been battling Lyme, West Nile, EEE, etc., now so bad as to be nearly public health crises.
The upside of the more open weave Deluxe fabric is greater breathability and coolness.
Hennessy Hammock afficionado and supporter.