Phylloxera caryae-semen Walsh.
Phylloxera caryae-semen Walsh.
Daktylosphara caryae-semen Walsh.
This is evidently closely related to Ph. deplanata. The galls of c.-semen are, however, much smaller, more strongly convex, projecting above, and of much finer and harder texture. They also greatly resemble smaller specimens of Ph. minima not withstanding the striking difference in the life-history of the two species, viz.: the production of a winged, migratory form in Ph. minima and the absence of such in Ph. c.-semen.
Walsh was led from the apterous nature of the species to consider it Coccidous rather than Aphidian, and in discussing the relative generic value of winged and apterous gall-making species, remarks that "Carya possesses at least two Coccidous galls, namely, caryae-vena Fitch, which I find exclusively on the Shell-bark Hickory in August, and which is described by Fitch as Aphidian, and doubtingly referred to the genus Pemphigus, and caryae semen Walsh MS., a gall of the size and shape of a cabbage seed, which I find in prodigious numbers on the leaflets of the Pignut Hickory in July." And further on, in a foot note, he says : ' 'That these two galls are Coccidous, not Aphidian, may be inferred from the fact that the tarsi of the mother-lice are 1-jointed, not 2- jointed. And besides,Dr. Fitch himself describes the mother-lice of caryaevenae as laying eggs, and the same remark applies to those of Carym semen; whereas all true gall-making Aphidians that are known to me are viviparous so long as they live in the gall. Moreover, all gall- making Aphidians that are known to me remain in the gall till they have reached maturity and most of them acquired wings; whereas in these two galls the young larvae, almost as soon as. they have hatched out, stray away to found new galls, leaving the mother-lice behind them to lay from time to time fresh eggs."
With our present knowledge of the Phylloxerinae we know that Walsh erred in forming this opinion. The tarsi of both species mentioned are (like those of all other known species of Phylloxera) plainly 2-jointed, he having simply overlooked the small basal joint; while the economy of the species producing winged females shows that they all originate from eggs, numerously deposited by the stem-mother on the walls of the gall. Maintaining this erroneous position regarding the Coccidous character of c. -semen, he refers it later to Shimer's genus Dactylosphaera, to include all those species which produce, or are supposed to produce, nothing but apterous individuals and proposed for all others, producing a winged generation, the name of Xerophylla. In the latter publication, after much discussion, he gives a short description of the gall and its architects on page 23, as follows:
"Gall Carya-semen , n. sp. made by Dactylosphoera caryae-semen , new species. On the general surface of the leaflets of the Pignut Hickory (Carya glabra) in prodigious abundance, a sub- globular, smooth, seed-like, hollow, sessile gall, 0.06-0.10 inch in its widest diameter, subhemispherical above, rather flatter below, with a nipple-like opening in the middle. Walls of the gall rather stout, fleshy and not woody. The external color is greenish-yellow above and pale green below, with the open central nipple whitish. There are frequently as many as 100 of these galls on a single leaflet. Inside may often be found as many as three or four mother bark-lice, similarly shaped and of the same yellow color as those of the vitifolia gall, but on the average rather smaller and accompanied, in the same manner, by eggs or very young larvae, or both. As with the mother bark-lice of the galls vitifoliae Fitch, caryae-venae Fitch and caryae-fallax Walsh MS., the antennae of this mother bark-louse are three-jointed, joints i and 2 short and subequal, and joint 3 longer than 1 and 2 put together. The young larvae are about 0.01 inch long and of the usual shape. Almost as soon as hatched — as is also the case with the larvae of all the allied galls — these larvae stray away to found new galls. The galls themselves are very abundant about July 24th,' but by the 12th of August they were almost all empty and gaping open below."
Dr. Shimer, referring to the same species, confounds it with his Dak. globosum, which forms a similar though much larger gall on the same leaves and produces a winged generation. Speaking of the young of the smaller galls he says "the young larva usually leaves the gall as soon as hatched and proceeds, as does the ' grape-leaf louse" (D. ? vitifoliae), to construct a new gall."
The following notes, made in the West some years ago, will amplify the somewhat brief description of the gall by Walsh :
Description of Gall. — Transeverse diameter 0.3-2 mm or slightly larger. Vertical diameter 0.2-0.5 mm. Hemispherical and more prominent above than beneath and frequently depressed at the centre; the depression often running out to one side. More or less projecting beneath, with a tendency to become somewhat conical, terminating in a short nipple, with a round or slightly oval orifice, surrounded by 4-10 or more rather stout and profusely pubescent recurved bracts, completely closed when young. Upper surface smooth, yellowish- green to brownish-yellow. Rather tough and leathery and slightly semi-transparent at the centre if held toward the light.
This gall is usually extremely abundant on infected trees, often to such an extent that every leaf is completely covered. I have counted on some of the smaller leaflets over 300 of these galls, many of which, to the number of 2-5 or more, were confluent.
This appears to be an exclusive western species and has been found at Kirkwood and elsewhere in the Mississippi Valley, upon Hicoria glabra, maturing during the latter half of July and early August.
