OF WASHINGTON, VOLUME XV, 1913. 91 



It was noticed that the feeding larvae had the head and forepart 

 of the body buried in the cavity they had eaten out of the stem, but 

 that the posterior part of the body was standing out free in the water. 

 This would suggest that, at will, they are able easily to pierce the 

 wall of the stem with their modified spiracles and that perhaps the 

 larva has some other means of securing a supply of oxygen. It 

 would be very interesting to know the composition of the gas in the 

 interior of these stems, as in all probability it is not the same as that 

 of atmospheric air. The adult Donacia collected at the time these 

 observations were made has been identified as D. cincticornis. 



The two following papers were read by title and accepted for 

 publication. 



OBSERVATIONS ON THE EGG PARASITES OF DATANA 

 INTEGERRIMA WALK. 



BY H. M. RUSSELL, Bureau of Entomology. 



The writer collected the data contained in this paper while sta- 

 tioned at Orlando, Florida, during the years 1907 and 1908. The 

 summer of 1907 seemed to have been favorable to Datana inte- 

 gerrima Walk., the black walnut caterpillar, as the colonies of 

 larvre of this insect were extremely abundant on the pecan and 

 destroyed the foliage extensively. This abundance apparently 

 resulted in a great increase of the egg parasites of this insect as the 

 eggs of the last generation in the fall of 1907 were largely parasitized 

 by minute Hymenoptera. This probably accounts for the small- 

 ness of first brood in 1908. At the time of the fall abundance the 

 writer collected a number of egg-masses of Datana integerrima and 

 from these reared four species of parasites. The writer is indebted 

 to Mr. J. C. Crawford, of the National Museum, for the determi- 

 nation of three species and to Mr. A. A. Girault for the determina- 

 tion of Trichogramma minutum Riley. Of these, Trichogramma 

 minutum Riley belongs to the Trichogrammidse and Baryscapus 

 sp. belongs to the family Eulophidse, subfamily Tetrastichinse, 

 Telenomus sphingis Ashm. belongs to the family Scelionidae and 

 the fourth, Ooencyrtus sp. belongs to the family Encrytidae, tribe 

 Mirini. 



The eggs of the host were collected from August 23 until about 

 the 10th of October, from the various pecan grooves around the 

 station, and each mass was placed in a glass vial. Daily observa- 

 tions were made and the parasites removed and recorded in the 

 notes. These records have been placed in tables, as rendering the 

 data more quickly and easily available to the reader. 



