African Wildlife & Environment Issue 83

GARDENING FOR BIODIVERSITY

and tiny hairs on the back can cause severe irritation if the caterpillars are handled. If you grow G. occidentalis , you may even attract a fairytale into your garden as the plant is one of two known food sources for the caterpillars of Snow White Chasmina tibialis . These moths are entirely white, except for the yellow and black front legs. In addition to supporting so many moths, G. occidentalis is also the recorded larval host-plant of two species of butterfly, but these are not of the very colourful variety and they are moth-like in several respects. All this insect activity attracts another group of garden wildlife in the form of predators such as antlions, assassin bugs, robber flies, spiders and numerous others. Patient gardeners realise that these are nature’s own pesticides and that there is never any need to use poisons to fight our indigenous insects, as they are part of a well-balanced food chain. It is a law of nature that predators always breed more slowly than their prey. Imagine how lions would overrun Kruger Park if they bred as fast as impalas! But we all know how fast some pests can multiply, sometimes even overnight. A further law is that predators always choose to attack the weaker individuals. This all adds up to a simple, tragic scenario.When we poison the pests in our garden, we also kill the predators which breed much more slowly. They may be destroyed directly by the poison, or indirectly when they eat poisoned insects which have become too ill or lethargic to get away. The remaining pests now have fewer predators to keep them in check, so a population explosion occurs.The horrified gardener puts out even more poison and quite predictably, through the same sequence, the last few predators in the vicinity are eliminated and the pests multiply uncontrollably. A vicious cycle is set up, so that the more poison you use, the more pests you’ll have and the more poison you’ll need. Of course, none of this is mentioned on the poison packet! G. occidentalis is available from most indigenous nurseries or can easily be cultivated from fresh seeds or hardwood cuttings. It grows quite fast, prefers sun or part shade and is reasonably frost-resistant. Although deciduous for a short period where winters are very cold or dry, it is generally evergreen. It has become popular as a garden subject in the USA, especially in California, where it is known as the Lavender Starflower. Besides being a good browsing plant for game and stock, the wood of G. occidentalis is known to have been used by the San to make bows because it is strong yet pliable while, as it doesn’t splinter, it

them. The wasps’ larvae are assured of a fresh juicy meal as they devour the caterpillar alive! One member of the group of processionary moths, Anaphe reticulata , with its gregarious caterpillars, is also known to use G. occidentalis as a food-plant. This medium-sized moth is quite attractive with cream wings decorated by a network of bold brown lines. Unfortunately, however, it is the caterpillars, being more noticeable as they live in colonies of two hundred or more, which often send ill-informed gardeners scurrying for the spray can in a mad panic. Although they can completely defoliate even a large specimen, indigenous vegetation has evolved to live with this phenomenon and will recover very quickly. In fact, the plant is often stimulated to grow faster as a result of these insects feeding on it. Once there is little left to eat the caterpillars trek, in convoy head to tail, in search of the next plant on which to feast. Just as noticeable as this curious habit is the fascinating communal cocoon (bagnest) that they construct; it ranges from the size of a golf ball to that of a football. Another interesting species that uses G. occidentalis as a larval food-plant is Serrodes korana (previously known as Serrodes partita ), which has caterpillars that are nocturnal, feeding at night and hiding by day. Often called the ‘Catapult Moth’, on account of the V-shaped mark near the base of the forewing, this is a member of the fruit piercing group of moths. Unlike other moths, which feed mainly on nectar or do not feed at all after their caterpillar stage, this moth has a strong, sharp proboscis to pierce into fruit and extract sap. It is related to species found in tropical Africa, Asia and South America which feed on the eye secretions of mammals. Because such a moth inserts its proboscis into animals’ eyes to obtain the liquid, it spreads ocular diseases among cattle and sheep. But fortunately our moths in this genus are harmless! The larvae of another of our indigenous moth species, which usually feed on G. occidentalis , have adapted to alien pine trees as a food source as these sadly seem to have become more readily available. These Brown-tail Moths Euproctis terminalis are smallish to medium sized with deep yellow, satiny wings and a dark brown tuft or tail on the end of the abdomen, hence their common name.The caterpillars, which are very unpopular with pine plantation management on account of the damage they do, become black when mature with a narrow white line running along the centre of their backs. Long white tufts of hair are found on the side of each segment,

34 | African Wildlife & Environment | Issue 83 (2023)