Insecticides and Hungry Caterpillars

Bushland remnants, riparian areas, public parks, reserves and wetlands provide important habitat for our butterflies in Brisbane. This is where the majority of native larval host plants are found, and where Council supported catchment and bushcare groups work on enhancement of habitat and connectivity.

Native vegetation on many large private properties across our city contributes significantly to the overall health of butterfly communities. These properties are often registered under the Land for Wildlife program. Not underestimated in their importance should be the many gardens in Brisbane. While native provenance may in many cases have been replaced with introduced plant species, they will nevertheless attract butterflies, not least because they offer nectar sources. 

Every home gardener loves seeing butterflies visit flowers and obtain nectar. It becomes more difficult when those butterflies have offspring and start chewing the leaves of the home gardener's pride and joy. Often treatment with insecticides will follow and may have unintentional consequences. 

Eliminating the next generation of butterflies is only one of the effects. Insecticides are likely to reach other invertebrate species which were not meant to be targeted, among them many important pollinators, and affect an entire ecosystem, however large or small. 

Butterflies are indicators of environmental health. Rather than removing them in all their growth stages, we should celebrate them. Caterpillars temporarily 'prune' a shrub, but the leaves will grow back, and by avoiding insecticides a patch of nature will have been preserved. 

Image: Sylvia Alexander