sick cactus plant closeup with selective focus

problem plant damage skin cactus nature garden succulent eggs fungus houseplant species bug nest pests insects small mealy bugs attack sucking scale epidemiology aulacaspis insect disease cacti infected parasite lice mealybug sick cochenille botany angiosperms caryophyllales cactoideae opuntias cactoids suculents science pesticides biology pest unhealthy bacterial coccidae infested closeup selective focus