Abstract: Ferns and insects live on the earth together more than 300 million years, but the interaction is rare known. A field surveys was hold in Sangzhi County of Hunan province about the insect larvae on Pteris spp. We found 89 Noctuidae larvae and 21 Tenthredinidae larvae on 42 bracken ferns belong to four species. The larvea of Tenthredinidae mimiced the indusium through appearance and color, and feeded on immature leaves. By contrast, the larvea of Noctuidae feeded on spores hiding under the indusium, whose color turns white to buff, with brown spot sometime, as another kind of soral crypsis. Meanwhile, a jump spider
of prey was observed, which may be attracted by the larvea. The spider acts on the mature sporophyl, carrying several spores. These discoveries give us a good insight into the interaction and co-evolution among ferns, insect larvea and spider.