July 2016: Newsletter 359

June Day Meeting

We gathered at Doris’ Matua home on a fine morning with a comfy group of 17 members. Her small section is packed with a wide range of bromeliads, flowering shrubs orchids and a busy vege garden, with broad beans looking great.

We roamed around the property finding little treasures tucked into corners, happy orchids in a small shade house and even swan plants with caterpillars and chrysalis.

June Evening Meeting

Present: 30 members.

Vice-president Conrad Coenen talked about pests that attack our orchids – a wide range of creatures can cause problems including, insects, slugs and snails and rats and mice.

So what is an insect and which ones will I find on my orchids? The ones that cause the most problems are small, usually have 6 legs, have a hard exoskeleton (like a crab), breathe through pores in the sides of their bodies, feed by sucking-chewing-rasping and breed very rapidly in large numbers. Some insects eat the nitrogen and deposit unwanted sugar on the leaf, leaving a yellow patch. The sugar or honey-dew often attracts ants and becomes black with sooty mould.

Which are the most common that I have to worry about?

Aphids: There are many varieties and colours, slightly pear shaped with 6 spindly legs, these gather on the more tender parts of the plant, most commonly on new leaves and flower parts. They can multiply at an alarming rate with each female laying 60-80 babies (they skip the egg stage) a day. When the plant becomes crowded or is dying the female lays winged babies that can fly to other plants. Ants will also carry aphids around as they gather the sugar that the aphid excretes.

Woolly aphids: Still an aphid, as above, but this insect tends to breed and stay in tight bunches, hiding beneath a waxy white blanket that acts as protection from predators. Often the first indication is a spreading yellow area on the surface of the leaf as the nitrogen is removed from the cells, especially noticeable on Cattleya leaves.



Scale: A small hard-shelled insect that sticks to the stem or leaf, each variety differs in shape and colour, usually round or oval. A scale crawler hatches from an egg and moves over the plant to find a vein it can stick its piercing mouth-part into and settles down to form the protective shell. Eggs are laid under the shell and as the crawlers hatch they emerge to spread over the plant. Sugar is again secreted as waste and ants can quickly spread the crawlers even further.


Mealy bug

Mealy Bug: This looks like a mix of scale and woolly aphids.
These small white crawlers look like a miniature slater with tails. They are very mobile and can hide down in the bark, inside the back of flowers and even in spring clips on flower stakes. When they settle into position they protect themselves with fluffy waxy threads. They also produce honey-dew that ants collect.

Thrip: A tiny, long earwig-shaped insect that rasps the surface of leaves, deforming and turning them silver.

Spider Mite: Minute reddish-brown spiders that cause yellow patches on leaves. Prefer softer leafed plants like Lycaste and will form webbing as protection. Prefers very warm temperatures with little air movement.

White fly: Tiny white-winged insects that mass on the lower surface of leaves of most garden plants. If you look closely at the leaf surface you will see hundreds of eggs and juveniles. Each breeding cycle  takes only 25 days, so it will take 3 sprays at 10-14 day intervals to knock out the invasion.

Other insects found among your orchids will be caterpillars (mostly from moth eggs), earwigs, wetas, beetles and even cockroaches.

So now you can identify what is attacking your orchids, how do you kill them? Conrad took us through the full range of insecticides that have been used for years and explained how and why many of these quite dangerous sprays have been either removed from the market or altered to make them safer. The insects themselves have cleverly become immune to many of these insecticides simply because of the vast number of life cycles that allow them to adapt and build resistance.

Sprays like Orthene, Attack, Carbaryl, Super Shield and others that you may still have on your shelf, do have a place in killing the insects and protecting your plants, but care must be taken when using them. Read labels very carefully to follow correct measurements, mix sprays as indicated, wear correct protective clothing and interchange insecticides regularly to avoid overuse.

There is a move away from those above to safer sprays that rely on fatty acids, oils and soaps to smother the insect by coating the surface to block breathing pores or strip away protective waxy surfaces. Nature’s Way, Mavrik, Spraying Oils and Neem, plus a host of others are on the shelves of the Garden Centres with full instructions.

There are some very simple, cheap alternatives that can provide much the same results: Using detergents, methylated spirits and cooking oils. If you venture on to the internet for alternative organic sprays you will find a wide range of recipes using garlic, tomato leaves, herbs and other ingredients.

The following recipes and suggestions were given by club members on the night:

Clean-up Spray: To 2 litres water add 15mls meths, 15mls cooking oil, 15 mls detergent. Shake regularly as you spray. With all oil-based sprays, keep newly sprayed plants out of bright sunlight.

Add Neem granules to the top of pots to deter ants, protect roots and be absorbed by the plant systemically to kill or damage biting insects.

Clean out all rubbish, old pots, ferns and weeds from under benches. Insects of all kinds use these host plants to winter-over and re-infect your orchids in spring.

Spray inside your orchid house with Ripcord. This long lasting oil-based spray will clean out any insects that crawl across the surfaces. Can also be sprayed on plants.

When you receive a new plant check it over very carefully. If in doubt, repot completely.

If you have a plant badly infected with scale, mealy bug or other insects, wrap a nylon stocking across the bark, tip the plant upside down and submerge the whole plant in a bucket containing spraying oil and an insecticide. Leave it there for an hour or so to suffocate and kill all insects and eggs.

If you suspect there may be wetas grazing on your plants place short lengths of bamboo around for the weta to crawl into. Check for occupants and put over the fence!

None of this report can convey Conrad’s wit, humour and hand-drawn flip charts showing the insects. Nor can I cover his years of experience in the horticulture industry.

Popular Vote June 2016


Conrad Coenen’s probable Vuylstekeara of unknown parentage was first.

Barry Curtis: Onc. sotoanum 2nd

Diane Hintz: Slc. Japanese Beauty ‘Sakura’ 3rd=

Conrad Coenen: Cirrhopetalum Elizabeth Ann‘Buckleberry’ 3rd=.

Display Plants

(* = Note correct &/or new name) ([? ] = Not identified …………………..)

Barry Curtis: Oncidium sotoanum (n.b. sotoanum is a new name for a pink Oncidium from Central America – which was known for years as Onc. ornithorhynchum. This name is now given to the species which is yellow and from Andean S. America.); Onc. Tsiku* Marguerite; Den. Colonial Surprise x Gai Ellen; Maclellanara Pagan Lovesong ‘Ruby Charles’.

Trevor and Pam Signal: Encyclia calamari.

Brian and Natalie Simmonds: C. Bowgata x Lc. Molly Tyler; Encyclia calamara – listed as Anacheilium calamarium with Encyclia calamara and Prosthechia calamara as synonyms. Den. Colonial Surprise x Yondi Star ‘Dark’; Den. victoriae-reginae x Kuniko (=Den, Mayumi) *.

Elizabeth Bailey: C. Magic Fire ‘Solar Flare’; Osmoglossum pulchellum; Masd. Lemon Meringue; Masd. colossus; Den. Vivian Snider; Den. Jonathan’s Glory; Dockrilla Black Pam x.

Barbara Nalder: Den. ‘Taurean’ (This name is not listed anywhere as a Dendrobium species or hybrid); Slc. Hazel Boyd ‘Elizabeth’ x Jewel Box ‘Scheherzade’ ( = Slc. Seagulls Adam Michael)*.

John Edwards: Dendrochilum glumaceum; Onc. Gold Dust; Calanthe vestita; Rodriguezia decora; Paph. Silvara Taupiri; Laelia gouldiana.

Wilma Fitzgibbons: Stenorrhynchos speciosum x sib.; Bulbophyllum (Cirrhopetalum) Elizabeth Ann ‘Buckleberry’ (flower spike).

Jan Missen: Coelogyne mossongeanum [?] – ? massangeana, syn.tomentosa; Masd.?.

Diane Hintz: Dendrochilum magnum var. latifolium; Dendrochilum uncatum.