6D Mr. Peringuey, a Note on the [^^g-> 



I should here state that the insects flying against the panes of glass 

 which cover the boxes, and on which the vapour from the ground 

 condenses, are glued against them and easily detected. 



At the time I placed those two vines in the conservatory [February] 

 there were several nymphs on the rootlets. Supposing that those 

 nymphs became the winged females, which I had collected later on, 

 they have required 56 days to assume the winged form.(^) 



On the 6th of December of the same year I brought from Modder- 

 gat a large quantity of insects, with which I stocked three Cape vines, 

 1 wild vine, 2 American Vitis Aestivalis, and placed also a small 

 amount of them, among which I could see no nymph, at the foot of 

 the very vine from which the exodus had taken place six months pre- 

 viously. On the 10th of January I got the first winged form from 

 that same vine, which up to date has given me twenty-four ; 

 vine No. 2, stocked in December, has given me eight. Two young 

 vines planted this year have given me nothing as yet ; neither have 

 the two American vines, nor has the insect taken to the wild species, 

 Cissus capensis. 



I do not believe that this is the final exodus, which I expect in May 

 or June, when the rainy season sets in. No other Apliidm have yet 

 appeared abroad. 



The result of those observations are thus somewhat different from 

 those observed in France. The young vine No. 1(''^), which has given 

 me last year fourteen winged females only, has given me twenty-four 

 this year, and it is in the last stage of decay. The two young vines 

 3 and 4 (which do not thrive very well) have as yet given me none. 

 It might be deduced from this that here the winged form is not pro- 

 duced in greater number during the first year of infection. 



Vine No. 2, stocked with insects from Moddergat, has, however, 

 yielded eight winged female from the 13th of Januarj^, i.e., thirt}-- 

 five days after it had been stocked ; and I conclude that the measures 

 taken to destroy the centres from which those insects came have been 

 instrumental in checking the first exodus, and in preserving the adja- 

 cent vineyards from contamination at any distance. 



The life history of the phylloxera presents, however, some difiicul- 

 ties which are not easily accounted for, and the theories of the late 

 Mons. Lichtenstein, which went far towards their solution, have not 

 been accepted by ever}^ entomologist. It is therefore with great 

 satisfaction that I record here a similar result to that obtained by 

 that distinguished aphidographist, viz., the development of the winged 

 form in about ninety days, with a nearly constant temperatui'e of 72° 

 Fahr. 



I hasten, however, to explain that the observations I have been 

 able to make have been too few to decide decisively the points still 

 obscure which I have been treating of. They must be repeated again 

 and again, under different climatal circumstances. They have only 

 been made in one locality, *ind atmospheric influence is well known to 

 act in many different ways on Aphidce. 



(^) It is very probable that a previous exodus had taken pLicc from that same vine 

 before I placed "it in the conservatory. 



(') Vino No. 2 being nearly dead was removed from the box in September, three 

 moaths after the exodus. 



