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Hormaphidinae : Nipponaphidini : Euthoracaphis umbellulariae
 

 

Euthoracaphis umbellulariae

California laurel aphid

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

Identification & Distribution

Adult apterae of Euthoracaphis umbellulariae are sedentary, aleyrodiform (=whitefly larva shaped), more pointed posteriorly, otherwise pill-box-shaped, black, and covered with white filamentous wax. The integument of the body is quite hard and rigid, with distinct sutures on the prosoma (=head+thorax) dividing it into a large quadrate central area, plus an anterior and two dorsolateral areas (cf. Thoracaphis spp., which have the dorsal area of prosoma entire, with no sutures). All hairs on the prosoma are fine, the longest of them 40-80 μm long (cf. Euthoracaphis heterotricha, which has two longitudinal spinal rows of long thick hairs, 80-125 μm long, in addition to many long and short fine hairs). The antennae are three-segmented, with a conspicuous round rhinarium near the apex of the middle segment, and a number of short spines at the apex of the third segment. The rostrum is short, and three-segmented. The legs are yellow, and conspicuously prominent for members of the genus. The siphunculi are represented by mere rings or pores. The abdomen is reduced in length, and often less waxed than the rest of the dorsum. The cauda is short and wide, and slightly constricted at its base. The anal plate is deeply bilobed. The apterae do not move after they once settle down, and soon become firmly cemented to the leaf surface, where they secrete considerable quantities of white-cottony wax which completely envelops them.

Note: Takahashi (1959) reports that Essig compared his Japanese specimens with those originally described in California, and confirmed there was no difference between them. Takahashi also synonomized Euthoracaphis cinnamoniae with Euthoracaphis umbellulariae. This was queried by Hille Ris Lambers (1966), but Blackman notes that specimens in the BMNH collection do not show any consistent differences between Japanese and Californian populations.

First image above copyright Krissa Klein, second image copyright Justin Paulin,
both under a creative commons licence.

Euthoracaphis umbellulariae alatae (not pictured) are jet black with little or no wax covering, standing out in sharp contrast to wax covered nymphs and adult apterous forms in the same colony. The antennae are five-segmented, with numerous annular secondary rhinaria. The body is widest across the front third of the abdomen, with four marginal tubercles on each side, and with the abdominal segmentation quite clearly defined. The siphunculi are mere thickened rings or pores, hardly distinguishable except in cleared specimens. The cauda is short, much wider than long, and slightly constricted at the base. The anal plate is distinctly bilobed.

We suspect the bright red nymphs in the first picture below are free-living early-instar nymphs of Euthoracaphis umbellulariae before they secrete wax and 'cement' themselves to the leaf - but we have been unable to confirm or refute this from any published account.

First image above copyright CA Clarke, second image copyright Merav Vonshak,
both under a creative commons licence.

The California laurel aphid was first described by Essig (1932) in California, where it is very common on California Bay laurel (Umbellularia californica), and is also recorded from sassafras (Sassafras albidum) and cinnamon (Cinnamomum spp.). Euthoracaphis umbellulariae live and feed on the leaf undersides. Some years later it was also found on leaves of cinnamon in Japan by Takahashi (1959). It seems likely that the aphid was originally introduced from east Asia into California, and not vice versa, because species in the same and related genera are all Asian, also populations in California are anholocyclic. The life cycle of Euthoracaphis umbellulariae in Japan is unknown but, since many Nipponaphidini form galls on winter hazel (Distylium sp.), Blackman suggested that this is their most likely primary host.

 

Other aphids on the same host

Primary host(s)

The life cycle of Euthoracaphis umbellulariae is unknown, but the 25% of Nipponaphidini whose primary hosts are known use winter hazel (either Distylium racemosum or Distylium stellare).

Secondary hosts

Euthoracaphis umbellulariae has been recorded on 4 cinnamon species (Cinnamomum brevifolium, Cinnamomum camphora, Cinnamomum japonicum, Cinnamomum pedunculatum).

Euthoracaphis umbellulariae has been recorded from 1 Umbellularia species (Umbellularia californica).

Euthoracaphis umbellulariae is the only aphid recorded from sassafras (Sassafras albidum) aside from, possibly, Aphis fabae.

Acknowledgements

We are grateful to Krissa Klein, Justin Paulin, CA Clarke (sea-kangaroo) & Merav Vonshak for making their images of Euthoracaphis umbellulariae available for use under a creative commons licence.

We have used the description of the species by Essig (1932) (as Thoracaphis umbellulariae), together with information from Takahashi (1959) & Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors (see references below) 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

  • Essig, E.O. (1932). A genus and species of the family Aphididae new to North America.University of California Publications in Entomology 6(1): (p. 4)

  • Hille Ris Lambers, D. (1966). Notes on California aphids, with descriptions of new genera and new species. Hilgardia 97(15), 569-623. Abstract

  • Takahashi, R. (1959). Some aphids related to Nipponaphis Pergande in Japan (Homoptera). Bulletin of the University of Osaka Prefecture Series B 9, (p. 8).