Body oval, yellow or green and also gray; body covered by layer of white mealy wax, allowing body segmentation to be visible; ovisac covers body; occurring on arboreal parts of plant; ovisacs often on spines or at base of spines.
This species was intercepted at U. S. ports-of-entry 10 times between 1995 and 2012, with specimens originating from France, Germany, Italy, Mexico, The Netherlands, and The United Kingdom of Great Britain and N. Ireland. We also have examined specimens taken in quarantine from Canada (Mammillaria); Chile (unknown host); Germany (cactus, Cereus, Echinocactus); Japan (Cactaceae); Mexico (Aporocactus, Corypantha, Echinocactus, Ferrocactus, Mammillaria, Sedum, Stenocactus, Strombocactus, Wilcoxia); The Netherlands (cactus); South Africa (possibly Avonia ustulata); Spain (cactus); Switzerland (cactus); The United Kingdom of Great Britain and N. Ireland (England)(Lobivia); Uruguay (Echinocactus). ScaleNet lists hosts in Aizoaceae, Epacridaceae, Euphorbiaceae, Malpighiaceae, and the majority of host species in Cactaceae. It is also most commonly intercepted on cactus. ScaleNet distribution records for S. mamillariae include several countries in the Australasian, Nearctic, Neotropical and the Palaearctic zoogeographic regions. One other species of Spilococcus, S. geraniae Rau (Mexico, on Crataegus) has been taken at U. S. ports-of-entry.