236 



PSYCHE. 



[August — December 1SS9. 



inent on the upper surface, and are 

 about one-fourth of an inch in diameter. 

 Each gall produces three of four small 

 gall-flies that emerge about the first of 

 July, copulating imm ediately and then 

 disappearing. Where they went no- 

 body knew, or seemed to know till I 

 found out their secret last spring. 



Before the leaves appeared I visited 

 a thicket of young oaks where I had 

 found these galls very abundant in past 

 years, hoping to find their progenitor — 

 whoever she might be — ovipositing in 

 the buds of these oaks — but I was too 

 early ; she had not begun her work. 

 But where was she napping at the time.? 

 This question was not by any means a 

 new one to me. 



The soft, sandy loam at the roots of a 

 clump of oak bushes, — softer because of 

 the effects of the frost that had but re- 

 cently left it, — yielded to my fingers and 

 I soon had one of the main roots laid 

 bare. Judge of the joyful surprise it 

 gave me to find the bark of this root a 

 solid mass of blister like swellings. 



Removing a portion of it with my 

 knife I found it literally full of minute 

 larvae, each imbedded in a mass of liv. 

 ing vegetable pulp, but so very small 

 and immature were these larvae that I 

 was certain that they could not arrive at 

 maturity in season for egg-laying in the 

 then swelling buds. 



I uncovered other roots of this and 

 other clumps of oaks, always finding 

 more or less of the larvae in the bark, and 

 at length, in some older blisters, I found 

 well grown cynipidous larvae, evidently 

 a year older than those first found, but 



still their maturity seemed too far oft' for 

 the work to be done within the next few 

 days. 



I collected on that and several close 

 succeeding days a quantity of bark con- 

 taining larvae, and, placing it in sand, 

 and in a glass case, found after three or 

 four days that several perfect gall-flies 

 had come out. Within a week or so 

 quite a number appeared, but the bark 

 deprived of the sap of the tree, no longer 

 furnished food for the young larvae and 

 they died. 



That nature, provident against the 

 extinction of her children, in this case, 

 keeps two generations in the larval state 

 at the same time seems absolutely cer- 

 tain, and I feel nearly sure there are 

 really three ; that the larger larvae no- 

 ticed will not appear until next spring, 

 and that the perfect insects were in that 

 state at the time I first found the galls. 



But I am asked : How do you know 

 that these root gall-flies are the pro- 

 ducers of X\\Q futilis galls } Perhaps I 

 cannot convince the querist, but the 

 proof I have to offer is as follows : 



Suftering in health from too close 

 confinement in my place of business 

 during the winter, as soon as the 

 weather would permit, I spent a part of 

 nearly every pleasant day in the open 

 air. I improved these hours in watching 

 my pets in the woods and thickets. I 

 found hundreds of gall-flies ovipositing 

 in the buds of oaks of various species, 

 flies of several species, and one of these 

 I found abundant on the low white oak 

 bushes. I captured many of them but 

 left unmolested far more than I cap 



