As part of the New Zealand International Science Festival, a series of workshops will be held at the Botanic Garden on why its staff buy and breed predators to control the number of other bugs.
"It is like playing God," winter garden curator Stephen Bishop said.
Staff at the winter garden had used predators as part of an integrated pest management system for more than five years, Mr Bishop said.
The predators, including Australian ladybirds and parasitic wasps, preyed on common pests found in the winter garden, such as mealy bugs and aphids.
"The predators only target their specific pest, so there is no danger of them attacking anything else."
Preferring the subtropical temperatures of the winter garden to the cold outside, the predators were unlikely to establish themselves outside the glasshouse, he said.
Sourced from a supplier in Pukekohe, the predator bugs were as expensive as the chemicals they replaced, "but from a health and safety point of view they are a lot better".
With pests developing resistance to chemicals, the predators were "an excellent alternative", he said.
"People think sprays are a quick fix to everything, but they aren't."
Parasitic wasps were released from a small jar several days ago, to control the number of aphids destroying some of the succulents in the garden.
"The first sign of infestation is the best time to release, because the population is so small," Mr Bishop said.
The wasps' technique for ridding the plant of aphids was relatively simple, he said.
The adult wasp laid an egg inside an aphid, the egg hatched and the larva ate the aphid from the inside.
The aphid swelled and the larva pupated into an adult wasp before emerging from the "aphid mummy".
"It is quite fascinating to witness all the carnage."
The free science festival workshop, Bug Wars, will be held on Tuesday, July 8, to Thursday, July 10, from 2.45pm to 3.30pm at the Dunedin Botanic Garden.
