SUPERFAMILY TINEOIDEA 129 



hosts, plants with evergreen leaves. Opuntia joints also 

 are evergreen. 



Whether found in shoots, prickly pear joints or leaves, 

 the mines of species of this genus are very long, very narrow, 

 more or less winding and, at least for most of their length, 

 involve but a single layer of parenchyma cells. The larvae 

 leave the mines to pupate. The cocoons of the leaf-mining 

 species are characteristic, of white or yellowish silk, and un- 

 usual in that they are decorated with a good many irides- 

 cent or pearly white globules. 



The smilax miner, Marmara smilacisella, works in the 

 leaves of several species of the genus Smilax, some of which 

 are commonly known as cat briers. Miss Braun found it on 

 Smilax hispida about Cincinnati, Ohio. She says that it 

 mines the upper side of the leaves, making a silvery white 

 narrow mine which even in its latter stages is no more than 

 2.5 mm. wide. There is a narrow central line of frass. 

 The mines wind about over the leaf, crossing and recrossing 

 and in smaller leaves involving almost the whole upper 

 surface. 



At maturity the larvae turn bright red, emerge from the 

 mine, and, in a fold under the edge of the leaf, spin yellowish 

 white cocoons with groups of the iridescent globules at the 

 ends. 



The arbutus miner, Marmara arbutiella, one of us (Mrs. 

 Tothill) has observed working on the Madrona tree, Arbutus 

 menziesii, in British Columbia, and extracts from her notes 

 have already been given in the introduction to this book 

 (p. 26). She noted further that mines made by these lar- 

 vae are very characteristic in appearance, for with their 

 cell-shearing mandibles they sever the cuticle of the leaf 

 from its parenchyma so adroitly that the colorless epidermis 

 is left almost "chemically clean. " The mine, therefore, 

 appears by reflected light to be a solid white line. 



In the first collection of mines of this species, made about 



