LEPIDOPTERA 631 



Family SCYTHRIDID^ 



This family includes a group of genera that are closely allied to 

 the Yponomeutidse and are included in that family by some writers. 

 I do not find that any tangible characters of the adult insects separat- 

 ing the two families have been pointed out ; but there appear to be 

 diifferences in the setal characters of the larvae (see Fracker '15). 



The family is represented in our fauna by only two genera, Scythris 

 and Epermenia, including twenty-two species. None of these species 

 has attracted attention on account of its economic importance. 



The larva? of Scythris magnatella feed on Epilobium. They are 

 solitary when small, folding over half of the leaf to the midrib in the 

 central part of its length, attached with web. Later they form con- 

 siderable web among the leaves. The pupa is formed in a delicate, 

 flossv web. (D3^ar). 



The larva of Epermenia pimpinella feeds by forming a puffy mine 

 on Pimpinella integerrima. The pupa is inclosed in a frail, open- 

 meshed cocoon on the under side of a leaf or in angles of leaf-stalks. 

 (Murtfeldt.) 



One of the more common representatives of this family is Scythris 

 eboracensis. The adult is a small black moth tinged with violet, with 

 a wing-expanse of about 10 mm. It is found on flowers. 



Family YPONOMEUTID^* 



In this family the ocelli are small or absent. In the more typical 

 forms the wings are comparatively broad, with the venation but little 

 reduced. In the fore wings all of the branches of the branched veins 

 are usually separate, and vein R5 extends to the outer margin. In 

 the hind wings veins Rs and Mi are well-separated. The first anal 

 vein is distinct in both fore and hind wings. 



Writers differ greatly as to the limits of this family ; some include 

 in it certain genera or groups of genera that by others are regarded as 

 distinct families. 



In its restricted sense the family Yponomeutidas includes about 

 fifty North American species; among these are the following. 



The cedar tineid, Argyresthia thuiella. — This is a small narrow- 

 winged moth, which expands about 8 mm. Its ground color is pearly- 

 white, with the fore wings dotted and marked with brown, especially 

 on the outer half of the wing. The larva feeds on the leaves of cedar, 

 and when full-grown spins a small, conspicuous white cocoon attached 

 to a leaf. 



The apple fruit-miner, Argyresthia conjugella. — The larva of this 

 species is a serious pest in the apple orchards of western Canada. 

 It is pinkish white in color and about 9 mm. in length. It burrows 

 in all directions through the fruit, causing it to deca3^ The winter is 

 passed in the pupal state. The cocoons are made under the bark on 

 the trunk of the tree or under leaves on the ground ; they are white, 



*An emended form of this family name, Hyponomeutidae, is used by some 

 writers. 



