RILEY — NOTES ON NAT. HIST. OF GRAPE PHYLLOXERA. 



283 



find their explanation not so much in the difficulty of supplying 

 the natural conditions, as in lack of experience as to what those 

 conditions were. 



Whether owing to the want of down on the Clinton leaf, or to 

 the fact that the minuteness of the eggs makes it about as difficult 

 to find them on a square four feet of earth surface as the prover- 

 bial " needle in a haystack," the eggs found on the vine in the 

 afore-mentioned muslin enclosure were very few compared to the 

 number of winged insects which must have come out of the 

 ground. It was also next to impossible to find, and quite impos- 

 sible to follow, the sexed individuals after hatching. In the pre- 

 pared jars, where the tomentose leaves of Labrusca were kept, I 

 obtained more satisfactory results ; for, while a few eggs were 

 laid on the surface of the ground, especially in the space between 

 the earth and (he glass, and a few others on the upper side of the 

 leaves, by far the larger number were attached to the under sur- 

 face, generally by one end and thrust between the natural down 

 of the leaf — evidently showing that this is the natural nidus cho- 

 sen. The winged mothers die soon after ovipositing, and their 

 shrivelled and decaying bodies adhere to the leaf-down. 



^Fig. 22.] 



Sexed Phylloxer.« : a, female vasiatrix, ventral view, showing egg through trans, 

 parent skin; b, do . dorsal view ; c, greatly enlarged tarsus; rf, shrunken anal joints as they 

 appear after oviposition ; ^, male cary^caa//*, dorsal view — the dots in circle indicating 

 natural size. 



By taking a leaf bearing eggs that are eight or nine days old 

 and enclosing it in a smaller, tightly corked, tube, the sexed indi- 



