4C 



JOURNAL OF HORTIODLTUKE AND COTTAGE GABDENEl;. 



( July IC., 11*9. 



on the abdominal segments. The Lead is always ooneealed by 

 tbe anterior pro'iibtriince of the buckler; tlie antenmi- aru 

 almost alwB.vB iuaclivo. Tlie abdomen, often short and cuu- 

 traoted, becomes elongated towards laying-lime, and there c«n 

 be easily seen one, two, or sometimes three eggs, iu a more or 

 less mature state. 



The egg sometimes retains its yellow colour fnr one, two, or 

 three days alttr it has been laid; more often, however, it 

 changes to a dullnrty hue. From five to cisbt days generally 

 elapse before it is hatched. The duration of this period de- 

 pends a good deal on the temperature. The quantity of egRs, 

 and the rapidity with which they are produced, are probalily 

 determined by a variety of circumstances — the health of the 

 insect, the quantity of nourishment it is able to obtniu, the 

 xveather, and perhaps other canses. A female which had pro- 

 duced six eggs at eight o'clock a.m. on the 20lh of August, had 

 fifteen on the 2l9t at fuur r.ii. — that is, she laid nine in thirty- 

 two Loare. Other females Iny one, two, or three eggs in 

 twonty-fiiur hours. The raaximnm quantity is thirty in five 

 days. The eggs are generally piled up near the mother with- 

 out any apparent order, but she sometimes changes her posi- 

 tion so as to scatter them all around her. They have a smooth 

 surface, and adhtre lightly to each other by means of a slimy 

 matter which nttiicbes to them. 



Phylloxera rnstatrjx (J, E. Plixnchou\ — Female specimens and their 

 CG^B, a, auteunie ; b, horns or suckers; c, egg plainly visible in the body 

 ol the insect; /, winged form of the insect. Ail ujaguitied. 



Hatching takes place through an irregular and often lateral 

 rent in the egg, the empty and crumpled membrane being 

 found «mong the other eggs in different stages of hatching. 



During the first period of their active life — two, three, four, 

 or five days, as the case may be— the insects are in an erratic 

 state. They creep about as if they were seeking for a favour- 

 able situation. Their movements are more rapid than those of 

 adnlts. They appear to inspect, as it were, with their antenna' 

 the surface they travel over. The movements of the antennio 

 are generally alternative, and, if the comparison may be par- 

 doned, are not unlike the two sticks of a blind man, which he 

 nses to explore the ground he is about to tread. 



After a few days of this errant life, the young insects seem to 

 fix npon a spot to settle in. Most frequently this is a fissure 

 in the bark of a Vine, where their suckers can be easily plunged 

 into the cellular tissue, full of saccharine matter. If you make 

 a fresh wound on the root by cutting off a little piece of the 

 bark, you may see the "pncerons," range themselves in rows 

 around the wound, and once fixed, they apply to the root their 

 antennas, which appear like two small divergent horns. At 

 this period of their life, about the thirteenth or fourteenth 

 day after their birth, they are more or less sedentary ; but they 

 change their places if a new wound is made on the root, which 

 promises a fresh supply of food. 



What Sdnse is this which directs those snbtei raneons "pnce- 

 rons " towards the place which is most suitable for them ? It 

 cannot be sight, as their eyes are merely coloured spots, and 

 they creep as if thiy were blind. It cannot be hearing, be- 

 cause they seek no prey but a vegetable tissue. It is probably 

 the sense of smelling ; and one may wcUask if the nuclei which 

 appear enshrined iu the last articulations of the antenna' are 

 not the organs of this function, the seat of which has been so 

 mnch disputed ? Among these non-adult insects, attached by 

 their suckers to the Vine rout, aro seen, hero and there, some 

 of middle size. Their colour is a deeper orange, the abdomen 

 shorter and more squarely formed. These individuals are 

 more sedentary than tho others. I have sometimes imagined 

 they might be wingless (apterous) males of the species ; but as 

 nothing has happened to confirm this very problematical 

 hypothesis, and as I have seen undoubted females much re- 

 sembling these examples in colour and form, I incline to the 

 belief that there are no sexual differences among them. A 



kind of doable moalt precedes the adult state. The first takoc 

 place shortly after birth, the second after laying time. Some 

 uncertainty, however, hangs over the number of these changes, 

 as the cast'OfT skins are often found mixt-d up with groups ol 

 " pucerons " of different ages, and it is difficult to distiuguiab 

 them. On the morbid taberosities of the fibrous Vine toots, 

 or on tho oilshoots of the roots, tho " pucerons " (perhaps 

 better nourished) seem to pass more quickly through the dif- 

 ferent phases I have described ; but excepting that their colour 

 is paler, they present no marked diflerence. 



Tho ringed form of the Phylloxera might easily be taken 

 for a separate species. The rare specimens which I have seen 

 have all come from the " pncerons " nouiished on the newly- 

 attacked Vino radicles. In their infant, or it might be called 

 their larva state, they resemble those which I have suggested 

 may be males, but tho buckler soon becomes more strongly 

 marked than in these last; and a kind of band seems distinctly 

 to define tho separation bet.veen this and the abdomen. The 

 sheaths of the wings, triangular-shaped and of a greyish colour, 

 appear on both sides of the buckler. It is easy to predict the 

 advent of a winged insect from this chrysalis. When one ol 

 these nympha; is seen to quit its place and to crawl over the 

 root, or up the side of the bottle where it may have been put, 

 its transformation is near. Soon, instead of a sort of pupa, a 

 beautiful little fly appears, whose two pairs of wings, crossed 

 horizontally, are mnch larger than its body. 



It impossible to doubt the identity of thi# insect with the 

 " puceron" which formed one of the swarm on the Vine root. 

 The details of the structure of certain organs — the autennoe, 

 claws, tarsi, and suckers — establish their identity. 



The horizontal position of the wings complotly distinguishes 

 the Phylloxera from tho true Aphis, whose wings are always 

 more or less inclined upwards. The two larger wings obliquely 

 oboval and cuneiform, have a lineal areoluun the larger basilary 

 half of their outer edge; and this is enclosed in an interior 

 nervure, which answers, I suppose, to the radial muscle. 

 One single oblique nervnre (or corneous division) is detached 

 from this last, and reaches to the inner edge. Two other 

 lines start from the end of the wing, and, becoming narrower 

 as they proceed, advance towards the oblique nervure but end 

 before reaching it. These are not, poihaps, uer>urcs, but rather 

 folds, for I have observed them absent. 



The inferior wings, both narrower and much shorter, have a 

 marginal nervure running from the base to the middle, but it 

 loses itself in a gentle protuberance, which the wing shows in 

 this place : a radial nervure runs parallel to the first, and dis- 

 appeara before it reaches the same spot. 



Tho eyes, black and relatively very large, are irregularly 

 globular, with marked conical nipples ; their surface is granular, 

 but a pointed depression is observed in the centre of each 

 glandule. A round eye- shaped spot occupies tho centre of the 

 forehead. 



Among fifteen winged specimens of the Phylloxera which 

 have come under my notice, not one has presented any sexual 

 difference. Almost all of them laid two or three eggs, and their 

 death, which happened soon after, may have been caused by 

 their imprisonment iu the bottles. Their eggs resembled those 

 of the wingless Phylloxera, and though they were only two or 

 three in number, they completely filled the abdomen of the 

 mother. They were easily seen by placing the insect under 

 the microscope. I do not know how long the eggs remain be- 

 fore they are hatched, or if they always produce the winged 

 form of the insect. It is probable that these winged individuals 

 serve for the transportation of this insect plague to a distance : 

 not that their wings would serve them for a rapid flight — they 

 are too inactive, they move them very little, and in rising from 

 the ground their horizontal position is preserved. My obser- 

 vations were, however, made under very unfavourable condi- 

 tions, tho insect being in a state of captivity ; but I suppose 

 that even in a natural state the wind is the principal agent for 

 the dispersion of the Phylloxer.a, as it is for many of the in- 

 sect tribe. In nny case, the discovery of this form of the 

 Pbyllo.^cra provided with wings, and evidently fitted for an 

 aerial life, is suflicient to explain tho hitherto embarrassicg 

 fact of the rapid spread of the Vino plagues. As to the spread 

 of the disease from one Vine to another, the wingless "puce- 

 rons " may suffice for this, a;, grouped in great numbers about 

 the lower part of unhealthy Vine stems, they might easily 

 attack the Vmes ne.'.rest them, even if they be heiiltby. It 

 may be asked in what manner these insects mannge to travel 

 from one Vine stock to another, and how they contrive to reach 

 the fibrous roots of the newly-attacked stocks? Do they 



