Abstract:

Among the invertebrates, some insects are able to produce natural silk fibres which can serve as an alternative to the threads of the spider’s web. The larvae of the caddis-fly make use of a multifunctional silky floss in producing hunting nets and residential tubular structures. Many species of caddis-fly build their capture webs in fast-flowing rivers. Therefore we suggest that such fibres must be strong. However, these webs have been studied and researched previously, taking into consideration the webs’ shape and the geometry of the meshes. This paper presents preliminary results concerning some of the web material’s morphological properties and tensile strength. We investigated the product of silk gland coming from Hydropsyche pellucidula, which is one of the most common caddisflies in Polish lowland rivers. Our researches proved that a cross-section of caddis-fly fibres is circular, with an average diameter of 10 μm. The mean tensile strength of the fibres investigated is 45 cN/tex (5.7⋅109 N/m2), and is comparable to the strength of most spider thread.