162 JOURNAL, OF ENTOMOLOGY AND ZOOLOGY 



stant sympathy, kind criticism and helpful guidance enabled me to 

 successfully complete these observations. 



Materials. — The round galls occur commonly on only one spe- 

 cies of goldenrod, Solidago canadensis. This goldenrod grows 

 along the roadsides, on the wet ground, especially In the open moist 

 places near a stream and with plenty of sunshine. The galls are 

 not always abundant; sometimes there are patches of goldenrods 

 free from galls entirely. In some gravelly pastures, patches are 

 found having galls on almost every stem. For the purpose of this 

 study galls have been gathered from seven principal localities about 

 Ithaca, viz., Cascadilla Gorge, Fall Creek Gorge, Six-Mile Creek, 

 South Hill, Cornell Heights, Forest Home and Percy Field, on 

 dates ranging from September, 1913, to September, 1914. The 

 total number collected and examined is 3,300. 



The first young gall was found on June 24, about 6 mm. long 

 and 5.1 mm. wide. This is the earliest time for the galls to start 

 growth. They reach full maturity In the last part of August. The 

 mature galls were found first with exit holes In the last part of 

 April. 



The size of the gall in full maturity varies very much. The 

 length varies from 16 to 36 mm., the average Is about 25 mm., and 

 the width varies from 9 to 29 mm., the average Is 20 mm. 



THE FLY {Euros ta solidaginis Fitch) 



The fly Is the only one of the tenants which is responsible for the 

 formation of the galls. It prepares the home for itself and also 

 for several guests. It was first described by Asa Fitch In the First 

 Report on Insects of the State of New York, 1855. The full 

 description of the fly is in Monographs of the DIptera of North 

 America, 1862, by H. Loew, and in the Canadian Entomologist, 

 Vol. 24, pp. 120-123, by Rev. T. W. Fyles and W. M. Brodle. 

 None of these has said anything regarding its life history. Its 

 emergence from the gall has been carefully observed and described 

 by Mrs. A. J. Snyder, as recorded in the Canadian Entomologist, 

 1898, pp. 99-101, but other Important activities during its life, as 



