Vol. 32, pp. 165-168 September 30, 1919 



PROCEEDINGS /^ 



OF THE 





BIOLOGICAL SOCIETY OF WASHINGTON Q 



NOTES ON GARGAPHIA TILIAE WALSH, THE LINDEN 



LACE-BUG. 



BY HARRY B. WEISS. 



The following notes are the results of observations made dur- 

 ing the summers of 1918 and 1919 at Uhlerstown, Pa., where 

 the lace-bug Gargaphia tiliae Walsh was fairly abundant on 

 lindens growing along the canal. 



During the last of May and first of June adults appear and deposit eggs. 

 The adult feeding at this time is quite scattered and shows as numerous 

 white spots on the upper leaf surfaces. The eggs are inserted in the lower 

 leaf surface and occur in clusters of from 60 or less to 300. Their bases are 

 inserted in the tissue and the eggs project at right angles to the lower surface 

 although many lean in all directions. The upper leaf surface just above 

 the egg mass is usually discolored and brown. 



After hatching the whitish or brownish-white nymphs feed in compact 

 clusters on the lower leaf surfaces which results in discolored, light, some- 

 what circular areas on the upper surfaces. Later these areas become brown 

 and dead. The feeding takes place on any part of the leaf and does not ap- 

 pear to be confined to tissue more or less near the midrib as is the case with 

 several species of Corythucha. The nymphs are always found feeding in 

 groups and do not scatter as they become older. 



During the incubation period of the egg, a female lace-bug is always in 

 attendance and each colony of nymphs usually has a female watching over 

 it until the members are full grown. Fink 1 has observed a similar occur- 

 rence in connection with the eggplant lace-bug, Gargaphia solani Heid., and 

 states that "when migrating from one leaf to another the female adult 

 usually directs the way and with her long antennae keeps the nymphs to- 

 gether or rebukes any straggler or deserter." Unfortunately, no migra- 

 tions of G. tiliae were observed, but it is quite probable that the adult acts 

 in a similar way. 



The eggs require about a week for hatching and the combined nymphal 

 stages about three weeks, making a month from egg to adult. Adults of the 



1 Fink, D. E., The Eggplant Lace-Bug, Bui. 239, U. S. Dept. Aerie. Bur. Ent. 

 33— Pboc. Biol. Soc. Wash., Vol. 32, 1919. (165) 



