Scotorythra rara (Lepidoptera: Geometridae)
Scotorythra rara (Lepidoptera: Geometridae)
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The green form is the most common. Note that except for the smaller size of the final instar, the first two of these forms are extremely similar to those of S. euryphaea.
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There is wide variation among the adults as well as the larvae.
This was the only true leaf-feeding native moth that I successfully reared from alien plants. Early-instar Scotorythra caterpillars, presumably rara, were also found on many other species of plants, but I only included here those plants on which it completed larval development. On ginger, most caterpillars did not survive, and those that did were usually malformed upon emergence as adults. On sugi, most did not survive past early instars. One made it as far as the prepupal stage, when it died. On Psidium cattleianum, strawberry guava, caterpillars can survive for awhile, but do not complete development. (There is evidence to suggest that some of the caterpillars on strawberry guava could have been S. euryphaea. Conservatively I have assumed that all Scotorythra on alien plants were rara, lacking proof of the contrary.)
S. rara does quite well on blackberry and A. melanoxylon, presumably due to their taxonomic proximity to the native Hawaiian hosts Rubus hawaiiensis and Acacia koa.
Larval development time varies greatly depending on the host plant. It is 5-6 weeks on Cheirodendron trigynum, while on Elaeocarpus bifidus or Vaccinium calycinum it can take 11 weeks or more. Interestingly, S. rara suffers somewhat lower parasitoid attack on the latter two plants.