1892. J 43 



This experience seemed strongly to confirm the idea that the ? 

 viridella had special business on the upper portions of these oak trees. 

 We accordingly obtained some small branches from the top of one, 

 and on these I confined the moths I brought home. The next day 

 (June 4th) I saw three several moths laying their eggs, and doing so 

 in a manner that convinced me they were now doing so in the ordinary 

 and proper way. The moth climbs up the petiole of a leaf, proceeds 

 some half an inch along the midrib underneath, and then pierces it 

 with the spear that arms the ovipositor and deposits the eg^, pro- 

 ceeding then a tenth of an inch or so and repeating the process. The 

 whole operation takes only 20—25 seconds, and is accompanied by 

 thrusting movements that agitate the whole moth. 



The sample of oak thus brought home and provided for them was 

 very short in the shoots, but the leaves were of a very robust succu- 

 lent character, about 3 to 4 inches long, and the petioles and midribs 

 were especially large and soft, remarkably so as compared with equally 

 young and juicy leaves from this neighbourhood. This may account 

 for the aberrant procedure of last year, and for viridella being local. 

 On dissecting one of these midribs I found it to contain three eggs 

 within a very short distance. The midrib contained a woody centre, 

 and a very succulent bark about 2/3 mm. thick, and the eggs were 

 laid in this bark in a slanting position, just touching or against the 

 wood, and with about as great a thickness of bark over them as they 

 themselves occupied. I found it impossible to be sure of any trace 

 of wound in the epidermis, although I had seen the moth pierce it 

 only a few minutes before. Yet the egg itself occupies a compara- 

 tively large space, and must be passed through a very appreciable 

 opening, and the space it occupies must be made by breaking down a 

 number of cells of tissue, and probably the thrusting movements of 

 the moth I observed were the effective agents in doing so. 



By searching a week later on the trees, I succeeded in finding one 

 egg laid in a precisely similar manner, thus confirming absolutely that 

 this is the natural locus of oviposition of this species. We searched 

 earnestly both then and later for signs of the young larva mining the 

 midrib, but without finding a trace, though we did find cicatrices sug- 

 gesting that the larva had dropped out very shortly after hatching, 

 and without having done anything, unless perchance to eat a direct 

 way out, and swallow some sap on the way. We entertain little doubt 

 that this is the actual procedure, the rest of the larval life being spent 

 on the ground. I was unable to maintain the freshness of the leaves 



