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YOUR GARDENING QUESTIONS THIS MONTH

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CHILLI CHEWER

QWe had a great crop of chillies and peppers but some 'Wildfire' chillies had patches of discoloured flesh and a small hole. The seeds were brown to blackish and obviously affected by something. One chilli had a pink caterpillar inside. What is it? JEAN DAY, NELSON

ABugman Ruud Kleinpaste identified this as the poroporo fruit or stem borer, Leucinodes cordalis, previously known as Sceliodes cordalis.

This moth is native to New Zealand and is found in the North Island and in Marlborough, Nelson and eastern coastal areas as far south as Dunedin. It’s also found in Australia.

The host plants for the caterpillars include solanum relatives, eggplants, pepino, tomatoes, potatoes, and various nightshade species including poroporo plus datura, capsicums and chillies.

Adult moths are pale brown with speckled triangular wings. They are active in early summer. After mating the females lay eggs on developing fruit or on the underside of leaves. When the eggs hatch, the caterpillars chew a hole through the skin of a fruit or the midrib of a leaf. Young caterpillars burrow under the skin, but older ones burrow into the fruit to feed on the developing seeds.

After moulting five to six times the fully-grown caterpillar turns red before leaving the fruit. It is thought that the colour makes the caterpillar harder for predators to see as it only comes out at night.

The caterpillar spins a cocoon covered with debris for camouflage and pupates for a week to 10 days. There are one or two generations a year. Caterpillars forming cocoons in February remain there until warmer weather in spring.

All stages of the lifecycle are predated by various birds, insects, spiders, parasitic moths or fungi. Don’t bother spraying – flick off the red eggs if you spot them and encourage diverse populations of beneficial insects and birds in your garden.

BUDDLEIA BUGS

QSome slimy little green bugs that I have never seen before are infesting a common old buddleia in my garden and the infestation seems to be limited to just that tree. I want to get rid of that tree anyway but would like to get of the slimy critters first. CHRISTINE GOBLE, MIDHIRST

AIt’s the biological control weevil Cleopus japonicus which was introduced into New Zealand in 2006 to control the spread of Buddleja

davidii. Spread by fine, windblown seed, buddleia is a major weed that grows anywhere, even in poor soils. Thickets establish quickly, preventing growth of other plants. The damage done to native bush and forestry plantations outweighs its usefulness as a nectar source for butterflies.

Cleopus larvae and adults eat buddleia leaves, and can defoliate plants and eventually kill them. Barbara Smith

WHO LIVES HERE?

QCould you please identify this strange nest found on branches of eucalyptus we planted on our lifestyle property some 20 years ago? We are in North Canterbury and have not come across anything like this before. SYLVIA ROSIE, EYREWELL

AThis sturdy cocoon is sheltering the pupa of an emperor gum moth. An adult moth may cut its way the following spring but can stay inside from two to five years waiting for optimal weather conditions.

Adult moths measure 120-150mm, but only live for a couple of weeks when they mate, lay eggs and die. The caterpillars are bright green with a yellow stripe down the side. They are large and robust, so they are good ones for children to care for and observe. My young sons were fascinated by their prodigious production of poo! Barbara Smith

SICK CAMELLIAS

QThe leaves of my ‘Cinnamon Cindy’ camellias have browny/ black splotchy marks that don’t rub off. They don’t get much sun and are about 10 years old, but have flowered prolifically and been really healthy until the last six months or so. ALICE SPENCE, AUCKLAND

AIt is not easy to identify the problem without understanding the site, soil and climatic conditions but it appears to be a mineral deficiency.

Purpling of the older leaves indicates phosphate deficiency and the new leaves show symptoms of nitrogen deficiency which indicates they are underfed. This may be caused by restricted root growth, depleted soil nutrients, insufficient water or too much water.

Fertilising with an acid fertiliser well-watered into the soil could help the alleviate the condition. Hamish Cheetham, NZ Camellia Society