12 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



has a striking black and white striped appearance. The venation 

 is given in figures 2, 3 and 4 (pi. 8). A marked feature of this 

 species is the costal fold in the hind wing of the male shown in 

 figure 4 (pi. 8). 



Alar expanse 8 mm. 



In summer the entire life cycle of the insect from egg to imago, 

 is completed in a trifle over a month. 



It is very improbable that this species should ever prove of 

 much economic importance. Though common, its feeding does 

 not kill or seriously disfigure the infested leaves. As we have 

 noted the larvae only attack the newer leaves at the ends of 

 branches and leaders. This specialized food habit coupled with 

 the scarcity of their proper food supply during fall Affectively 

 prevents them from becoming overabundant for more than a 

 short period during mid-summer. Parasites and predators also 

 play their part. Four species of Hymenoptera, 1 parasitic on 

 the larvae have been reared, and on two occasions Chrysopa 

 larvae were found attacking the gracilariid in its mine, piercing 

 the mid-rib with their mandibles and sucking the juices of the 

 larva within. While wandering about after leaving their mines 

 a number also fall victims of the spiders and birds; but these 

 factors of natural control are of secondary importance as com- 

 pared with the failure of large numbers of the fall larvae to secure 

 a proper food supply. 



In conclusion the writers wish to thank their good friends 

 August Busck- and Drs. Adam Boving and Charles R. Ely for 

 many helpful suggestions. Mr. Busck has also contributed the 

 drawings of the wing venation (pi. 8, figs. 2, 3, 4) for this paper. 

 All the other drawings are the work of J. J. DeGryse. 



EXPLANATION OF PLATES. 



PLATE I. Egg, work and cocoon. 



Fig. 1, blotch mine made by larva after it leaves the mid-rib in search 

 for more food. 



Fig. 2, opening out by the larva on leaving mid-rib in order to pupate. 



Fig. 3, egg (greatly enlarged). 



Fig. 4, cocoon decorated with globules. 



Fig. 5, normal mode of feeding in chestnut leaf; egg (O); point where 

 larva emerges from mid-rib (ep). 



PLATE -II. Larva in the first and second instars. 



Fig. 1, mandible (ventral view). 



1 Sympiesis flavipes Ashmead, Pseudopanleles ni gripes Roh., an Arthro- 

 lytus sp. and a single undeterminable male of the tribe Oinphalini. (Det. 

 by S. A. Pi,ohwer.) 



