Caterpillars of the silk moth genus Hyalophora (Lepidoptera; Saturniidae) construct multilayered cocoons that function as overwintering housing during the pupal to adult developmental period. While all cocoons share the primary function of protecting the developing moth, cocoons spun by different Hyalophora silk moth species vary significantly in architectural features and in the level of intraspecific cocoon-type polymorphism. We compared the cocoons of Hyalophora species found throughout North America and investigated the evolution of architectural variation. We first characterized and compared the architectural features of cocoons at all three cocoon sections (outer envelope, inner envelope, and the intermediate section that separates them), and found that variation in the outer envelope underlies the differences in architecture between cocoons. Phylogenetic analysis indicates ancestral polymorphic architecture (both “baggy” and “compact” morphs), with diversification within Hyalophora for both monomorphic “compact” cocoons, and increased intermediate space and silk in “baggy” lineages. The evolution of these traits suggests a potential functional role for the different cocoon architectural forms.

蚕蛾（Hyalophora）（鳞翅目； Saturniidae）的毛毛虫构造了多层茧，它们在development到成年的发育时期起着越冬的作用。尽管所有茧都具有保护飞蛾的主要功能，但由不同的Hyalophora蚕蛾物种纺出的茧在建筑特征和种内茧型多态性水平上却有很大差异。我们比较了透明质酸的茧在整个北美发现这些物种并调查了建筑变化的演变。我们首先对所有三个茧部分（外壳，内壳和分隔它们的中间部分）的茧的结构特征进行了比较，发现外壳的变化是茧之间结构差异的基础。系统发育分析表明祖先的多态结构（“宽松”和“紧凑”形态），在Hyalophora中多样化，既有单形“紧凑”茧，又在“宽松”世系中增加了中间空间和丝。这些特征的演变表明不同茧结构形式的潜在功能作用。