240 DAVENPORT ACADEMY OF SCIENCES. 



of the other species found upon Hicoria. They resemble more 

 closely those of certain of the Cecidomyidcs occurring on different 

 species of oaks and other plants. 



They always form, either along the main rib or more frquently 

 along the transverse veins, shorter or longer folds or plaits pro- 

 jecting more or less evenly from both sides, though usually more 

 prominent above, where they form elongate ridges or carinse, 

 which are often transversed by 3-5,, or more, short, elevated 

 branches, about equal in length to the diameter of the gall. The 

 opening or slit is always on the underside and, while fresh, is 

 tightly closed except at the outer end, and covered by a delicate 

 white or greenish pubescence which also more or less completely 

 covers the entire surface beneath. The color is generally yel- 

 lowish-green, though very frequently also brownish or purplish. 

 Two or more are often confluent, so that their length varies from 

 6-14™™- or more, and their diameter from 2-3"""-. 



The gall begins to form early in May. It occurs not only upon 

 Hicoria tomentosa but upon several other species of Hicoria and 

 is widely distributed over the eastern half of the United States, 

 having been observed from New York to Florida, and west as far 

 as Illinois and Missouri. 



No winged migratory female has yet been observed, but the 

 most remarkable fact is that I have been unable to discover in 

 any of the many galls examined from 1880 to 1890 a sexual form, 

 though examinations were made during different months. The 

 only occupants thus far found in these galls were the true stem- 

 mothers (of which 1-3 have been observed in the same gall) , 

 their eggs and the wingless sexuparse in different stages of devel- 

 opment. 



By the middle of August, when the majority of the galls had 

 become dry and empty, but a few remained still green and con- 

 tained the still living, though much shrunken, stem-mother, a 

 small number of eggs and a few larvae, but no migrants or sexual 

 individuals. 



On July 19, 1890, when many of the galls still contained their 

 usual inhabitants, extended and careful search was made to dis- 

 cover the whereabouts of the larvae after leaving the galls. 

 Small colonies, absolutely identical with those found within the 



