Asiphum sacculi Gillette

Collections. In pseudo gall of crumpled leaves with edges turned in, on Populus tremuloides. Colorado: Estes Park, Manitou, Pingree Park, Skyway and Ward. Fundatrices June 13 to Aug. 9, alate viviparae June 13 to Aug. 20; not common.

Pachypappa sacculi (Gillette)

The fundatrix is wax-dusted, slate grey with brown head; BL 4.5-5.0 mm. It forms a large bag-like gall on P. tremuloides, with edges and tip of leaf curled downward (Harper 1966; as Asiphum). In western USA (Arizona, Colorado, Utah, Washingtom, Alaska) and across Canada (British Columbia, Alberta, Quebec, Ontario and Nova Scotia). Progeny of the fundatrix are all alate, with dark olive-green abdomen, BL 3-4 mm. Host alternation to Picea spp. has now been confirmed by DNA bar-coding, and a redescription provided of the apterous exule (BL 0.9-1.8 mm) (Pike et al. 2012). Anholocyclic overwintering may occur on spruce roots (Pike et al. 2012). 2n=10.

Asiphum sacculi Gillette

Asiphum sacculi Gillette, 1914b :65; Gillette and Palmer, 1934:217; Palmer, 1952:356.
Pemphiglachnus kaibabensis Knowlton, 1938a :264.

This gall-forming aphid is relatively rare in the counties of Nova Scotia studied, found only twice in two different locations in Antigonish County on aspen poplar (Fig. 56). In the Fairmont Road region one small tree was studied over a period of three summers. Each year in late June or early July this same tree was infested with this leaf-pocket gall. None of the adjacent poplars observed in the same region were so infested. Unfortunately when the region was revisited on the fourth summer, the plot had been cleared with the resultant end of the observations on this tree. Gillette (1914b:66), the original describer of this species, reports that “all the young of the fundatrix, the second generation, become winged and leave the galls”. He also reports finding the two empty galls near the half-way house, Pike’s Peak. If this species has a summer alternate host which is unknown, and which is implied in Gillette’s comments, how is it possible to find this same leaf-pocket gall on the same host in three consecutive summers, and not find it on any nearby aspens?

From the facts at hand it appears that the species is monophagous, and if so, would account for the observations given. The fact that Gillette found some empty galls, does not necessarily imply that they have migrated. Syrphid larvae predators have been observed in some galls opened, which by this means could dispose of the contained aphids.

Specimens of this species were at first verified by M. E. MacGillivray as A. rosettei , her determination being based solely on alatae in balsam. Upon further comparison with Gillette’s A. sacculi (1914b:65, figs. 10-14) and figures 56 and 57 in this paper, there is little doubt that the species is A. sacculi Gillette. His description of the fundatrix and nymphs fits these specimens as does also the peculiar leaf-pocket gall.

The fundatrix is very large, oval and dull gray and pulverulent. The nymphs have a dark olive green abdomen and gray head and thorax, the abdomen being white tipped on five lateral tufts along the abdominal margins, and with intersegmental darker bands transversely placed across the dorsum. The wings of the alate second generation are slightly smoky; head and thorax blackish, abdomen dark olive-green.

Collections: In leaf-pocket pseudo-galls on Populus tremuloides Michx. (trembling aspen). ANTIGONISH COUNTY, Fairmont Road, July 4, 1950 (429); June 28, 1951 (501); June 26, 1952 (501); West River Road, July 30, 1952 (652).

Asiphum sacculi n. sp.

I first saw the gall of this louse about eighteen years ago when on a mountain trip some twenty miles or more northwest of Fort Collins. I did not meet with it again until the present summer, when, on July 13th, I found two of the leaf pockets characteristic of this species in Estes Park on twigs of Populus tremuloides about six miles apart and at an altitude of about 7500 feet. On August 9th, four more of the galls were taken near the Half-way House on Pike's Peak, at an altitude of about 9000 feet. In two of these galls there were no living lice. In each of the occupied galls taken (four), there was one large stem-female present, with a large number of her offspring in all stages of development up to the adult alate lice. There were no adult apterous lice and all that were half grown or more gave evidence that they were to get wings. In the breeding cages the alate lice began at once to deposit young with long beaks. In every case the lice were accompanied by a species of large black ant.

The Gall. An infested leaf becomes very much enlarged, and somewhat thickened with the edges turned in so as to make a heart shaped pocket, and the apex of the leaf is extended and turned back as shown in Plate XV, Figure 10. The color of the infested leaf is yellowish green, and lighter than the healthy foliage surrounding it.

Asiphum sacculi Gillette

[A photo of this gall appears on page 2 of the pdf]

This species was described from Colorado by Gillette (1914) and recorded from Utah by Knowlton and Bischoff (1939). Palmer (1952) considered Pemphiglacnus kaibabensis described from Arizona by Knowlton (1928) to be a synonym.

A. sacculi has been found in the foothills and mountain areas of southern Alberta since 1959. It forms a pseudogall on Populus tremuloides Michaux by causing a leaf to increase greatly in area and its sides and end to fold over (Fig. 1). In the gall are the fundatrix and her offspring with large numbers of ants. A. sacculi has also been found in Ontario on P. tremuloides (G. A. Bradley, personal communication).