INTERESTING INSECTS

By N A Martin (2017)

Red-cross mirid

This endemic mirid is found throughout New Zealand. It is predatory and found on a variety of plants. It occurs in city gardens and parks as well as native ecosystems.

Conservation status: Widespread, not threatened.

The red-cross mirid has been caught from October to May. There are probably several overlapping generations. There are likely to be fewer generations in cooler parts of the country.

Adults are found on leaves of plants with potential prey. The female has a background colour of yellow-green while the back ground colour of the male is paler and sometimes has a darker thorax (middle section of body) and head. Both the males and females have distinctive red patterns on their front wings and thorax. Typically, they have a red longitudinal stripe behind the eyes, a diagonal red line on the forewings and a red cross. The diagonal line may be linked to the red transverse band. In some specimens the red markings may be darker, almost black.

The female has an ovipositor, at the tip of her abdomen, that is used to insert eggs into leaves or young stems.

Nymphs hatch from the eggs. There are five nymphal stages, each is called an instar. Nymphs go from one stage to the next by moulting (changing their skin). During moulting, the skin on the dorsal side splits and the next stage pulls itself out of the old skin. First instar nymphs are like small wingless adults. The third instar has small wing buds and only those of the forewing are visible. In the fourth and fifth instars both pairs of wing buds are visible. and are largest in the 5th instar. Adults emerge from fifth instar nymphs.

Walking and flying

Nymphs and adults have three pairs of legs. Adults have two pairs of wings. The front chitinised pair cover the membranous hind wings when not being used for flying. Most of the forewing is coloured, the rest is membranous.

Feeding

Like other Hemiptera, the red-cross mirid 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 on to its prey and the stylets are then pushed into the prey. The inner pair of stylets form two tubes, one through which saliva is injected into the prey and a second through which digested juices are sucked up into the insect. Many mirids feed on plants and it is thought that the red-cross mirid may sometimes feed on plants.

Adult male red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRL]

Underside of adult male red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRJ]

Side view of adult male red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRM]

Front view of adult male red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRN]

Adult female red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRP]

Underside of adult female red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRT]

Side view of adult female red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRU]

Side view of adult female red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRV]

Adult red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae) on a puriri leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 2GRX]

Possible fifth instar (stage) nymph of red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae) on a puriri leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 2GRY]

Moulted nymphal skin of red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae) in colony of mealybugs. © All rights reserved. [Image: 2GRI]

Adult red-cross mirids have distinctive red markings on their dorsal (upper) body and wings. The female has a background colour of yellow-green while the back ground colour of the male is paler and sometimes with a darker thorax (middle section of body) and head. Both the males and females have distinctive red patterns on their front wings and thorax. Typically, they have a red longitudinal stripe behind the eyes, a diagonal red line on the forewings and a red cross. The diagonal line may be linked to the red transverse band. In some specimens the red markings may be darker, almost black.

Adult male red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRK]

Adult female red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae). © All rights reserved. [Image: 2GRR]

Adult red-cross mirid, Zanchius rubicrux (Hemiptera: Miridae) on a puriri leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 2GRW]

No natural enemies of the red-cross mirid are known. They may be caught by birds, spiders and predatory insects.

The red-cross mirid has been found in association with two species of psyllid and with mealybugs (the species name of the mealybug requires confirmation). This predatory mirid may feed on a variety of prey. Some predatory mirids also feed on plants but this has not been observed for the red-cross mirid.

Eyles AC 2005. Revision of New Zealand Orthotylinae (Insecta: Hemiptera: Miridae). New Zealand Journal of Zoology 32: 181-215.

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