INTERESTING INSECTS

By N A Martin (2017, revised 2018)

Green planthopper, Torpedo Bug, Large green plant-hopper

Poeciloptera acuta Walker, 1851

Poeciloptera cupido Walker, 1851

Cromna elegans Costa, 1864

Phalainesthes schauinslandi Kirkaldy, 1899

This adventive plant hopper from Australia was first reported in New Zealand by Kirkaldy in 1909. It is now found in the North Island and parts of the South Island. It occurs on its herbaceous, shrub and tree host plants in city gardens and parks as well as native ecosystems.

Conservation status: Widespread, a minor pest on some garden plants.

Nymphs and egg masses can be found on plants all year. Adults are commonest in Summer and Autumn. Many details of the annual cycle, life stages and behaviour of the Green planthopper are given by Myers in his informative 1922 paper on this insect.

Adults have green triangular wings that are normally folded to form a steep ‘roof’. The head and body are also green. There are two pairs of wings, three pairs of legs and one pair of antennae. The compound eyes are on the side of the head. A rostrum that holds the feeding stylets projects from the lower side of the head. The tip of the abdomen of females has an ovipositor for laying eggs.

After mating the female lays a flat oval cluster of eggs on a plant, usually on a leaf. There are 90-110 eggs in a batch, called an egg- cushion by Myers. The egg batch is initially white, but turns black due to a fungus that grows on the on the empty egg cases. After the nymphs hatch from the eggs, they usually stay near the egg mass for a short while before dispersing. Though they usually stay in small groups. The young nymphs are white and have a pair of white waxy filaments on each side of the sixth visible abdominal segment and two longer tufts at the tip of the abdomen. These wax tails are usually held close to the plant surface. The area around where they are living becomes lightly coated with wax. Like the adults the nymphs have a rostrum with the stylets for feeding, three pairs of legs and a pair of antennae. Nymphs go from one stage to the next by moulting. During moulting, the skin on the dorsal side splits and the next stage pulls itself out of the old skin. The second and third nymphal instars (stages) are increasingly green, while the fourth is green with some reddish markings. The fifth instar is white with pink markings. Older nymphs have wing buds. All nymphs have a white wax tail, with the wax mainly in two bundles. The tail is usually held flat against the plant, but can be lifted up and down. A little wax may be produced by other parts of the body.

Walking and flying

The nymphs and adults have three pairs of legs and when disturbed can jump. It is reported that the large nymphs can jump up to 60 centimetres, which is why they are called Torpedo Bugs in the USA.

The adults have two pairs of wings that are held over their body when not used for flying.

Feeding

Like other Hemiptera, the green planthopper has piercing and sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. When it wishes to feed, the bug moves the tip of the rostrum to a suitable part of the plant. The stylets are then gradually pushed into the plant. The stylets form two tubes, one through which saliva is injected into the plant and a second through which plants juices are sucked up into the insect. The insects feed on the phloem, on of a plants two systems for distribution nutrients. Excess liquid is secreted at intervals. Myers in his 1922 paper describes in detail the way the insects jerk their abdomen while excreting a bead of honeydew that emerges from between the tufts of wax filaments on their tail. After its emergence it is flicked away.

Adult green planthopper, Siphanta acuta (Flatidae): note that descending from the head, the proboscis that guides the stylets used for feeding. Creator: Tim Holmes. © Plant & Food Research. [Image: 2M43]

Top view of an adult green planthopper, Siphanta acuta (Flatidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M42]

Underside of an adult green planthopper, Siphanta acuta (Flatidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M41]

Two adult green planthoppers, Siphanta acuta (Flatidae) on Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M46]

Newly laid eggs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Coprosma rhamnoides (Rubiaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M47]

Eggs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Coprosma rhamnoides (Rubiaceae) and showing signs of developing nymphs. Creator: Tim Holmes. © Plant & Food Research. [Image: 2M48]

Eggs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Kawakawa, Piper excelsum (Piperaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4U]

Drawing of a flat egg-cushion of the Green plant hopper, Siphanta acuta (Flatidae). Creator: J. G. Myers. © Drawing published in New Zealand Journal of Science and Technology: 5:256-263, Figure 1. [Image: 2M5A]

Drawing of a first instar nymph of the Green plant hopper, Siphanta acuta (Flatidae). Creator: J. G. Myers. © Drawing published in New Zealand Journal of Science and Technology: 5:256-263, Figure 2. [Image: 2M5B]

Drawing of a third instar nymph of the Green plant hopper, Siphanta acuta (Flatidae). Creator: J. G. Myers. © Image by J. G. Myers. Drawing published in New Zealand Journal of Science and Technology: 5:256-263, Figure 3. [Image: 2M5C]

Drawing of a fifth instar nymph of the Green plant hopper, Siphanta acuta (Flatidae). Creator: J. G. Myers. © Drawing published in New Zealand Journal of Science and Technology: 5:256-263, Figure 4. [Image: 2M5D]

Nymphs hatching from eggs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Kawakawa, Piper excelsum (Piperaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4V]

Nymphs recently hatched from eggs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Parsonsia heterophylla (Apocynaceae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2M4X]

Recently hatched nymphs of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Kawakawa, Piper excelsum (Piperaceae). © Plant & Food Research. [Image: 2M4W]

Young nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Lemonwood, Pittosporum eugenioides (Pittosporaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4R]

Side view of a young nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Lemonwood, Pittosporum eugenioides (Pittosporaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4Q]

Small nymph of green planthopper, Siphanta acuta (Flatidae) and moulted skin on underside of a leaf of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3U]

Small nymphs of green planthopper, Siphanta acuta (Flatidae) and moulted skins on underside of a leaf of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3V]

Nymph of green planthopper, Siphanta acuta (Flatidae) on leaf of New Zealand flax, Phormium tenax (Hemerocallidaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4A]

Side view of nymph of green planthopper, Siphanta acuta (Flatidae) on leaf of New Zealand flax, Phormium tenax (Hemerocallidaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4B]

Nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Solanum nodiflorum (Solanaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4J]

Nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Solanum nodiflorum (Solanaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4K]

Nymph of green planthopper, Siphanta acuta (Flatidae) on leaf of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3X]

Large nymph of green planthopper, Siphanta acuta (Flatidae) on petiole (leaf stalk) of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3Y]

Large nymph of green planthopper, Siphanta acuta (Flatidae) on petiole (leaf stalk) of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3Z]

Underside of nymph of green planthopper, Siphanta acuta (Flatidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4G]

Side view of nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf stalk of Solanum nodiflorum (Solanaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4I]

Large nymph of green planthopper, Siphanta acuta (Flatidae) on underside of leaf of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M40]

Moulted nymphal skin of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Taraire, Beilschmiedia tarairi (Lauraceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4M]

The adult Green planthoppers are easy to distinguish from other insects by their bright green colour and shape of their wings that are held like a ‘steep roof’ and are sharply pointed at their tip. The most similar insect is the Grey planthopper, Anzora unicolor (Flatidae). It has a similar, though less angular shape and is blue-grey coloured.

The nymphs of the Green planthopper may be confused with those of the Grey plant hopper and the Passion vine hopper Scolypopa australis (Ricaniidae). Green planthopper nymphs have a pair of wax tails that are held close against the plant surface. There may be little wax on the plant around where they are living. Nymphs of the Grey planthopper produce a lot of wax from all over the body. The have long tails and ‘horns’ at the front. Nymphs of Passion vine hopper are red-brown with white markings. They also have a fluffy tail that is usually held upright.

Adult green planthopper, Siphanta acuta (Flatidae): note that descending from the head, the proboscis that guides the stylets used for feeding. Creator: Tim Holmes. © Plant & Food Research. [Image: 2M43]

Top view of an adult green planthopper, Siphanta acuta (Flatidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M42]

Adult Grey planthopper, Anzora unicolor (Flatidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M5L]

Two adult Grey planthoppers, Anzora unicolor (Flatidae) on Haloragis erecta (Haloragaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M5I]

Small nymphs of green planthopper, Siphanta acuta (Flatidae) and moulted skins on underside of a leaf of Coastal five-finger, Pseudopanax lessonii (Araliaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M3V]

Nymph of green planthopper, Siphanta acuta (Flatidae) on leaf of New Zealand flax, Phormium tenax (Hemerocallidaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M4A]

Nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf of Solanum nodiflorum (Solanaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4J]

Side view of nymph of green planthopper, Siphanta acuta (Flatidae) on the underside of a leaf stalk of Solanum nodiflorum (Solanaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M4I]

Nymph of Grey planthopper, Anzora unicolor (Flatidae) on Marsh ribbonwood, Plagianthus divaricatus (Malvaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M5S]

Colony of nymphs of Grey planthopper, Anzora unicolor (Flatidae) on Marsh ribbonwood, Plagianthus divaricatus (Malvaceae): note all the fluffy white wax. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2M5W]

Nymphs of Passion vine hoppers, Scolypopa australis (Hemiptera: Ricaniidae) on a leaf of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the fluffy wax tails held upright. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2M8E]

Adult and nymphs of Passion vine hoppers, Scolypopa australis (Hemiptera: Ricaniidae) on a leaf of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the nymphs with fluffy wax tails held upright. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2M8B]

Nymphs of the Passion vine hopper, Scolypopa australis (Hemiptera: Ricaniidae) on a leaf of Glossy karamu, Coprosma robusta (Rubiaceae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2M8M]

Two parasitoids and one predator are associated with the Green planthopper. No pathogens are known from the active stages or eggs.

Parasitoids

The Australian wasp, Green planthopper egg parasitoid, Aphanomerus pusillus (Platygasteridae) has been in New Zealand since the 1930’s according to a 1930 paper by Ted Gourley. The parasite was deliberately released into the USA to help control the green planthopper, which they call the Torpedo Bug, because of the long distnce that the nymphs can jump.

Planthopper parasitoid, Dryinus koebelei (Dryinidae) also comes from Australia and also parasitises the Grey planthopper. The larva may be seen on the planthopper nymphs where it is attched under one of the wing buds. The fully grown wasp larva leaves the now dead nymph and spins a cocoon in which it pupates. The adult female is very distinctive, the male less so.

Predators

The only recorded predator of the planthopper is the Steelblue ladybird, another insect of Australian origin. Myers in his 1922 paper reports that the ladybird devoured the eggs-cushions when placed in contact with them.

It is likely that the Green planthoppers are fed upon by other predatory insects, spiders and birds.

Nymph of Green planthopper, Siphanta acuta (Flatidae), with a larva of the ectoparasitoid Planthopper parasitoid, Dryinus koebelei (Dryinidae) that has its head inserted under the planthoppers wing bud. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2M2A]

Nymph of Green planthopper, Siphanta acuta (Flatidae), with a larva of the ectoparasitoid Planthopper parasitoid, Dryinus koebelei (Dryinidae) that has its head inserted under the planthoppers wing bud. Creator: Tim Holmes. © Plant & Food Research. [Image: 2M20]

Cocoon of Planthopper parasitoid, Dryinus koebelei (Dryinidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M21]

Nymphal of Green planthopper, Siphanta acuta (Flatidae), with skin of a larva of the ectoparasitoid Planthopper parasitoid, Dryinus koebelei (Dryinidae) after the parasitoid larva has left to spin its cocoon. Creator: Tim Holmes. © Plant & Food Research. [Image: 2M22]

Cocoon of Planthopper parasitoid, Dryinus koebelei (Dryinidae) with exit hole made by adult wasp Creator: Tim Holmes. © Plant & Food Research. [Image: 2M1X]

Dead adult female Planthopper parasitoid, Dryinus koebelei (Dryinidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2M1Y]

Egg batch of Green planthopper, Siphanta acuta (Flatidae), parasitised by Green planthopper egg parasitoid, Aphanomerus pusillus (Hymenoptera: Platygasteridae): note the exit holes made by the adult wasps. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2SBJ]

Front of adult female steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), showing the dark coloured head and front corners of the prothorax. Creator: Tim Holmes. © Plant & Food Research. [Image: 15WC]

Adult steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), about 4 mm long. Creator: Tim Holmes. © Plant & Food Research. [Image: 3HT]

Mature larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15W1]

Front view of larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15W3]

Egg batch of Green planthopper, Siphanta acuta (Flatidae), parasitised by Green planthopper egg parasitoid, Aphanomerus pusillus (Hymenoptera: Platygasteridae): note the exit holes made by the adult wasps. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2SBJ]

New Zealand host plants of the Green planthopper include native and adventive plants, including garden plants.

Feeding and plant damage

Like other Hemiptera, the green planthopper has piercing and sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. When it wishes to feed, the bug moves the tip of the rostrum to a suitable part of the plant. The stylets are then gradually pushed into the plant. The stylets form two tubes, one through which saliva is injected into the plant and a second through which plants juices are sucked up into the insect. The planthoppers feed on the plants phloem and secrete honeydew at intervals.

Green plant hoppers may be found on some garden plants and crops. If control is thought to be needed, commercial growers should contact their advisors and gardeners should contact a supplier of garden pesticides. If they are a problem in a garden, avoid growing very susceptible plants from where they can spread on to other plants.

Lariviere M-C, Fletcher MJ, Larochelle A. 2010. Auchenorrhyncha (Insecta: Hemiptera): catalogue. Fauna of New Zealand. 63: 1-228.

Myers,J.G. 1922: Life-history of (Walk.), the large green plant-hopper. New Zealand Journal of Science and Technology: 5:256-263.

Valentine EW. 1967. A list of the hosts of entomophagous insects of New Zealand. New Zealand Journal of Science. 10 (4): 1100-1210. This paper gives details of Gurley’s 1930 paper).

The New Zealand Plant & Food Research Institute Limited (Plant & Food Research) for permission to use photographs.

1 August 2018, NA Martin. Photo added of egg batch with parasitoid exit holes.