140 



the authors in Michigan correspond with those of Houghton in 

 England in 1903 on Recurvaria nanella, Hiibn., the synonomy of these 

 two species is now accepted by Busck. 



After the history of the species in Europe, and its distribution both 

 there and in the United States, are dealt with, the European host plants 

 of R. nanella are given, viz. : apricot, pear, apple, peach, plum, cherry, 

 wild plum, and hawthorn, the pear being the favourite ; it has also 

 been recorded as seriously attacking the peach. In Michigan, the 

 insect was reared from apple, peach, pear, plum, and sweet and sour 

 cherries, the infestation being hght on plum and cherry. In Penn- 

 sylvania, it was reared from a wild hawthorn. The Kieffer pear seems 

 to be resistant to the attack of the young larva in the autumn or leaf- 

 mining stage, as the mines are never developed to any great 

 extent and the larvae die. The larvae of R. nanella in the spring 

 attack both blossom and leaf-buds ; the insect bores into the bud, 

 eating the tissue, especially the young stamens and pistils of blossom- 

 buds. As the buds open, a web is spun amongst the leaves, causing 

 much deformation. 



Eleven synonyms of R. nanella, as well as descriptions of the adalt 

 larva and the pupa, are given. In Michigan, the first moths issued 

 in rearing cages on 22nd June 1913, the maximum emergence being 

 on 30th June, and the last moths appearing on 10th July. All attempts 

 to feed the moths in captivity failed, nor would they oviposit. In a 

 footnote, it is stated that as this bulletin was going to press, eggs were 

 received from Michigan, where they were obtained from moths con- 

 fined in glass jars. Some were loosely deposited among the hairs on 

 the underside of an apple leaf, for the most part along the veins of the 

 leaf ; others had been laid on a twig under the edge of a small scale. 

 In Michigan, the eggs commenced hatching about 15th July and the 

 larvae at once bored through the epidermis of the leaf on the under- 

 side. It is evident that the adult female in depositing her eggs lays 

 a number at one time on adjacent leaves, as the mines usually appear 

 in groups, several affected leaves occurring on the same or neighbouring 

 twigs. 



Upon the arrival of the first cold days of autumn, the larvae leave 

 the mines and construct small silken hibernacula in the bark, etc., 

 in which they pass the winter ; in 1913, this commenced about 12th 

 September and by the 17th practically all the larvae had disappeared 

 from the mines. The hibernating larvae on large trees, even where 

 the infestation is severe, are difficult to locate, being very small and 

 inconspicuous. After a few warm days in the spring, they begin 

 to appear ; the first larvae were observed working in the buds 

 in considerable numbers on 15th April. As a rule, the larvae 

 are to be found at rest within the silken nest they spin on the 

 opening leaves and it is therefore supposed that they are nocturnal 

 feeders. The larval stage covers on an average a period of about 10 

 months ; the number of moults was not accurately determined. 

 Pupation occurs under loose bark and occupies on an average about 

 19 days. On large trees, where there is a great deal of roughened bark, 

 the cocoons are difficult to find, but on young pear trees, where most 

 ol the bark is smooth, they will be found clustered in the crevices on the 

 trunk. A few larvae pupated among the leaves and debris on the 

 ground beneath the trees. From material collected in the larval and 



