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Eriosomatinae : Pemphigini : Pemphigus populicaulis
 

 

Pemphigus populicaulis

Poplar leaf-base gall aphid, Poplar leaf-petiole gall aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

In spring, Pemphigus populicaulis fundatrices form yellowish-green to creamy (sometimes reddish?) galls formed of the swollen base of a poplar leaf twisted with the broadened petiole (see first picture below). As such, the gall is very similar to those of two other American species, Pemphigus nortonii and Pemphigus populiglobuli. However, the exit from the gall for alatae is a small round hole on the underside between leaf and petiole (see second picture below) (cf. Pemphigus nortonii and Pemphigus populiglobuli, which have gall exits as a slit on the underside between the leaf and petiole). The galls are 10-13 mm in diameter. The fundatrix (not pictured) is pale yellowish to creamy, with a frosted appearance and slightly dusky appendages. The rostrum reaches between the first and second pair of coxae. Wax glands are in 6 dorsal rows, with none on the head. The body length of the Pemphigus populicaulis fundatrix is 2-2.9 mm.

Images above copyright Megachile, under a public domain licence.

The emigrant alate (see pictures below) has a blackish-brown head and thorax, a yellowish olive-green abdomen covered with blue-grey wax, and dusky brown appendages. The rostrum reaches between the first and second pair of coxae. There are 3-7 secondary rhinaria on the base of antennal segment VI (cf. Pemphigus nortonii, which has 5-11 rhinaria on the base of segment VI). The body length of adult Pemphigus populicaulis alatae is 1.7-2.0 mm.

Images above copyright Megachile, under a public domain licence.

Pemphigus populicaulis usually galls eastern cottonwood (Populus deltoides), but has also been recorded from other cottonwoods and quaking aspen (Populus tremuloides). Alatae emerge in July-September, and depart for an unknown secondary host. Water parsley (Oenanthe sarmentosa) and corn roots (Zea mays) have both been suggested, but neither has been confirmed. Pemphigus populicaulis is widely distributed in North America.

 

Other aphids on the same host

Pemphigus populicaulis has been recorded on 6 Populus species (Populus acuminata, Populus balsamifera, Populus deltoides ssp. deltoides, Populus deltoides var. occidentalis, Populus fremontii, Populus trichocarpa).

Acknowledgements

We are grateful to Megachile of i-naturalist for making the images of Pemphigus populicaulis available for use under a public domain designation.

We have used the species accounts of Fitch (1858) and Palmer (1952) along with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References

  • Fitch, Asa (1858). Insects infesting deciduous forest trees. Transactions of the New York State Agricultural Society 17(1), 781-854. (p. 845).

  • Palmer, M.A. (1952). Aphids of the Rocky Mountain Region: including primarily Colorado and Utah, but also bordering area composed of southern Wyoming, southeastern Idaho and northern New Mexico. Thomas Say Foundation, Denver. Full text