Opuntia spp. (except tiger pear & wheel cactus) Go to the project pages for [tiger pear](https://biocollect.ala.org.au/biocontrolhub/project/index/ffeb44d7-08d0-4627-a31b-6a6365700a18) and [wheel cactus](https://biocollect.ala.org.au/biocontrolhub/project/index/26ae9f28-4916-4579-afc0-7a9af3e19e0a) for further information on these weeds. All species of Opuntia have been declared [Weeds of National Significance](http://weeds.ala.org.au/WoNS/opuntioidcacti/). Opuntia spp. are mainly distributed in QLD and NSW, where they impede the grazing ability of pasture livestock and harbour pests. Opuntia spp. are drought-tolerant and resistant to burning, enabling established cacti to live for several decades growing in dense patches which hinder the growth of native species. Their sharp bristles may also cause injury to humans and animals. A successful biocontrol program from 1911-1939 resulted in the release of 20 biocontrol agents, 14 of which established in Australia. Since then, some species have subsequently died out, however 5 species remain active in controlling Opuntia spp. 1. Cactoblastis *Cactoblastis cactorum* 2. Cochineal scale insect *Dactylopius ceylonicus* 3. Cochineal scale insect *Dactylopius confusus* 4. Cochineal scale insect *Dactylopius opuntiae* 5. Tree pear beetle *Archlagocheirus funestus* Each biocontrol agent is effective at controlling specific species of Opuntia spp. Cactoblastis and Dactylopius spp. are the main agents used to control Opuntia spp. and have established many large populations across Australia since their releases in 1926 and 1933.
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