Attacks by predators and parasitoids on spider eggs are common. To counteract their negative effect, spiders have evolved a series of behaviours and features related to their egg sacs. In the genus Deinopis (Deinopidae) the tightly woven external layer of the egg sac seems to be an effective barrier. This layer consists of two sub-layers: the outer sub-layer is constructed of thin threads densely woven with an apparently hardened liquid that cements the threads together, and an inner sub-layer that seems to be even more compact and in which threads are not discernible. Threads of the external layer are presumably produced by the cylindrical glands, but other glands may be involved in production of the liquid substance.