WHEN INSECTS BECOME REAL PESTS
TIPS TO CONTROL PESTS WHEN GOOD INSECTS ARE NOT THERE TO HELP
Isat down with “bug man”, entomologist, Richard Piper and asked him what insects we could expect to see in our gardens this spring.
Richard told me: “Every year as the temperature warms up all the insect pupae that are buried in the ground or as cocoons that are hidden under the bark on trees say, ‘Hey wake up it’s spring’ and they’ll start to hatch out, and to mate.”
As we move around at night we’ll see more insect activities around lights. Many of these insects play an important role in the environment, they are what we call ‘beneficial insects’, they pollinate flowers and eat other insects that eat plants.
“There are many beneficial insects native to the Wet Tropics,” Richard emphasised. “There are two types of beneficial insects, the predators and the parasites. The predators are dragonflies, soldier flies and some are ground beetles. Then there are a host of parasitic insects which are very important; they’re the insects that lay their eggs into the larva or the bodies of pest insects.”
I asked Richard what beneficial insects would attack one of our new garden pests, spiralling whitefly. “There is a tiny, native wasp parasite, 2mm long, that lays its eggs into the nymphs of the spiralling whitefly.”
Spiralling whitefly has become a major horticulture problem, and favours poinsettia, acalypha and hibiscus shrubs, as well as strappy leafed plants like ground orchids.
“If the wasp is not around,” Richard said, “the best way to control spiralling whitefly is with a household detergent soap spray. This spray breaks the surface tension of the insect and upsets their chemistry.
“Other pests active in early spring are aphids, the lady bird beetle, both the adult and the larvae will feed on aphid, they love them and will clean them up quickly. There are wasp parasites and the lacewing larvae which are also important predators and the larva of hoverflies also feed on aphids.
“However”, Richard said, “look out for the 28 spotted lady beetle, which is a voracious feeder on vegetable plants like eggplant. The damage they do is easily seen with a serrated edge left around the plant’s leaf.
Again, soap spray is the best weapon against these pests,” Richard told me.
I asked Richard about the other major pest in potted plants, the large grub of the Christmas beetle and the rhinoceros beetle. “The grub is the immature stage of these beetles that causes the damage to plant roots. The female beetle, the one without the horn, lays around 50 eggs in potting mix or compost and when eggs hatch into hungry grubs they feed on the humus in the soil and when that runs out they eat the roots of plants.
“The best way to treat the problem, be it grub, ant, or cockroach is to immerse the pot in warm soapy water; the grubs should float to the top. Gravel on the top of the pot will stop the soil floating off and will also deter the mother beetle from laying eggs in the pot plant.
“Another spring pest problem is the leaf roller caterpillar and the best way to control it is hand picking. It’s really quite satisfying. Get out and get them when they’re young before they do too much damage.
“Coloured sticky traps are another method of controlling tiny insects like thrips and fruit fly. A blue sticky trap will attract thrips. Yellow sticky traps will attract whitefly, aphids and fruit fly. Sticky traps are also a good way of monitoring insect activity in the garden,” Richard told me.
“The bacterial control of caterpillars can be achieved with products like DiPel, but really you have to decide, do you have to have perfect leaves on every plant? Sometimes just enjoy the beauty of the insects.”