INTERESTING INSECTS

By N A Martin (2016, revised 2017)

Steelblue ladybird

Coccinella chalybea Boisduval, 1835

Orcus chalybeus (Boisduval, 1835)

Chilocorus cyaneus MacLeay

This adventive ladybird from Australia was first released in New Zealand in 1899. It is now the most common ladybird in Auckland, widespread in the North Island and present in the North of the South Island. It is found on trees and shrubs in native habitats and in crops, parks and gardens, where it feeds on a wide variety of insects and mites.

Conservation status: This adventive ladybird is widespread in the North Island and present in the North of the South Island. It helps to control some pests of economic and ornamental plants, but also feeds on native invertebrates in native habitats.

The distinctly coloured adults are about four millimetres long. The head, prothorax (first part of the middle body) and elytra (wing covers) are shiny dark metallic blue or green. The front of the head, front corners of the prothorax, and the femur of the front legs are yellowish brown in males. The legs are dark except the feet are mid brown like the antennae. Under the elytra is a pair of wings used for flying. The small head has a pair of compound eyes and two short antennae.

Female ladybirds lay yellow eggs probably near infestations of prey. Some eggs have dark material on top. A long, pale grey larva hatches from each egg. The newly hatched larva has long dark scoli (pointed fleshy extensions) with a single long seta (hair) at the tip. Older larvae have a darker base to the scoli which bear several dark setae. The three pairs of legs are used for walking. Larvae also use the tip of the abdomen for holding onto the substrate on which they are walking. As the larva grows, it moults (changes skin). There are four larval instars (stages). When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant and moults into a pupa. The pale pupa remains inside the moulted larval skin and is itself covered with short dense hairs. Adults hatch from pupae and mate. The length of time of each life stage depends on temperature, being shorter at higher temperatures.

Annual cycle

The ladybird overwinters (May-September) as adults as individuals or in small clusters (up to 10) in leaf folds and other nooks and crannies above ground in trees and shrubs. Occasionally clusters af many adults may be found. During winter adults are often seen basking in the sun. Eggs have been found in spring and summer while larvae and pupae have been found from late spring to early winter. There are two generations per year in Auckland with new adults appearing in January and second generation adults in March to April.

Walking and flying

Both adult and larval stages of this ladybird have three pairs of legs that can be used for walking. Larvae also use the tip of the abdomen for holding onto the substrate. Adults have wings and can fly.

Feeding

The adult and larval ladybirds eat a variety of small insects including scale insects, psyllids, whitefly and free living gall mites (Eriophyoidea). The jaws are the primarily structures used for holding and chewing the prey. Legs don’t appear to be used for holding prey.

Adults also feed on nectar in flowers and chew the white gum produced by damaged leaves of Eucalyptus species.

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

Adult steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), folding its wings under the elytra, wing covers. Creator: Tim Holmes. © Plant & Food Research. [Image: 15VX]

Front of an adult male steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), showing the yellowish brown head and front corners of the prothorax. © Plant & Food Research. [Image: 15VU]

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]

Underside of an adult steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), about 4 mm long. Creator: Tim Holmes. © Plant & Food Research. [Image: 15VW]

Eggs of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) with structures on top. Creator: Tim Holmes. © Plant & Food Research. [Image: 15WD]

Side view of eggs of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) with structures on top. Creator: Tim Holmes. © Plant & Food Research. [Image: 15WE]

Eggs of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) with no structures on top. Creator: Tim Holmes. © Plant & Food Research. [Image: 15W6]

Newly hatched larvae of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15W5]

Small larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15W0]

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]

Underside of larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15W2]

Rear view of larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). © Plant & Food Research. [Image: 15VT]

Steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), pupa in larval skin; note the wing buds and down covering the pupa. Creator: Tim Holmes. © Plant & Food Research. [Image: 15W8]

Steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), pupa in larval skin; note the wing buds and down covering the pupa. Creator: Tim Holmes. © Plant & Food Research. [Image: 15W9]

Steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), pupal and larval skins. Creator: Tim Holmes. © Plant & Food Research. [Image: 15WA]

Three overwintering adults of Steelblue ladybirds, Halmus chalybeus (Coleoptera: Coccinellidae) on underside of a leaf of a puriri, Vitex lucens (Labiatae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 1IVS]

Overwintering adults of Steelblue ladybirds, Halmus chalybeus (Coleoptera: Coccinellidae) on underside of a leaf of a karaka leaf, Corynocarpus laevigatus. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 29IP]

Overwintering adults of Steelblue ladybirds, Halmus chalybeus (Coleoptera: Coccinellidae) in crown of a cabbage tree, Cordyline australis (Asparagaceae). Creator: Frances MacDonald. © Frances MacDonald. [Image: 1IVQ]

Adult steelblue ladybirds are easily recognised by their circular shape and shiny steel blue or green colouring. Males have a yellow brown head and front corners of the prothorax. Larvae are also distinctive with their grey colour and long scoli (pointed fleshy extensions) bearing many setae. The pupae are also easily recognised by being in the skin of the mature larva and by being covered in down.

Front of an 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: 15WB]

Side view of adult male steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), note the pale front corner of the prothorax. © Plant & Food Research. [Image: 15VV]

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

Steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae), pupa in larval skin; note the wing buds and down covering the pupa. Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 29IQ]

In New Zealand the bodies of adult steelblue ladybird have been found in the guts of possums, Trichosurus vulpecula. They are probably also preyed upon by birds, spiders and predatory insects.

The dispersal stage of a mite that is a parasite of scale insects has been found on adult steelblue ladybirds. The mite, Hemisarcoptes coccophagus Meyer, 1962 (Acari: Astigmata: Hemisarcoptidae) uses ladybirds to spread from one scale insect colony to another. One of the nymphal stages of the mite has special adaptation for holding on to adult ladybirds. This process of dispersal is called phoresy.

Adult steelblue ladybirds also feed on nectar in flowers and chew the white gum produced by damaged leaves of Eucalyptus species. They may also feed on the honeydew, the sugary solution produced by sap sucking insects such as psyllids, whitefly and some families of scale insects.

Steelblue ladybird adults are known to feed on nectar. Many have also been found several times on leaves coated with honeydew of the giant willow aphid and the best explanation is that they were feeding on the honeydew.

Both adults and larvae feed on other insects. They have been recorded feeding on scale insects from four families, Asterolecaniidae, Coccidae, Diaspididae, Eriococcidae, and insects with scale like juvenile stages such as whitefly and psyllids. The have also been recorded feeding on moth eggs and free living gall mites (Eriophyoidea). In New Zealand a larva was seen to catch and eat a thrips larva and a tydaeid mite.

Larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) feeding on flax scale, Poliaspis floccosa (Hemiptera: Diaspididae). Creator: Tim Holmes. © Plant & Food Research. [Image: 15WF]

Moth eggs fed on by steeblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Eggs on leaflet of kowhai, Sophora sp. Creator: Tim Holmes. © Plant & Food Research. [Image: 18SW]

Moth eggs fed on by steeblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae). Eggs on leaflet of kowhai, Sophora sp. Creator: Tim Holmes. © Plant & Food Research. [Image: 18SX]

Larval skin and pupal case of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) on a puriri, Vitex lucens, leaf with pepper corn scale insects Epelidochiton piperis (Hemiptera: Coccidae); larvae were feeding on the scale crawlers. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29IL]

Eggs of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) on the underside of a Glossy karamu, Coprosma robusta, leaf with white erineum induced by Coprosma white erineum mitePhyllocoptes coprosmae Acari: Eriophyidae); larvae are known to feed on Eriophyidae mites. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29IM]

Newly hatched larvae of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) on the underside of a Glossy karamu, Coprosma robusta, leaf with white erineum induced by Coprosma white erineum mitePhyllocoptes coprosmae Acari: Eriophyidae); larvae are known to feed on Eriophyidae mites. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29IN]

Larva of steelblue ladybird, Halmus chalybeus (Coleoptera: Coccinellidae) feeding on flocculent flax scale, Poliaspis floccosa (Hemiptera: Diaspididae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2KLS]

Biological control of pests

Steelblue ladybirds from Australia were released into New Zealand in 1899 to control black scale, Saissetia oleae (Olivier, 1791) (Hemiptera: Coccidae), and 1905 to control gum tree scale, Eriococcus coriaceus Maskell, 1893 (Hemiptera: Eriococcidae). It is established in the warmer parts of New Zealand, but it is not known what effect it has on control of those scale insects which also have other natural enemies.

Steelblue ladybirds feed on a wide variety of small insects, including scale insects, psyllids and moth eggs. Its prey includes native insects as well as adventive species. The ladybird lives in crops, parks and gardens as well as native ecosystems. Its impact on herbivore prey is unknown, but judging by the numbers of ladybird adults and larvae on trees and shrubs, it must be consuming many insects including pests. Lo found strong indications that it can contribute to substantial control of soft wax scale, Ceroplastes destructor Newstead, 1917, and Chinese wax scale, Ceroplastes sinensis Del Guecio, 1900 (Hemiptera: Coccidae) in citrus orchards.

It is unlikely that this ladybird would be deliberately released into New Zealand today. Before a potential biological control agent is given permission to be released considerable information on its biology and prey is now required. The benefits from the proposed release need to outweigh any possible risks. The steelblue ladybird has a broad host range that would pose a risk to native insects and a significant contribution to effective control of a pest would need to be demonstrated.

Diverse habits of 'ladybirds'

Not all ladybirds eat insects; some feed on mites. Other species eat plant leaves and are pests especially in some tropical countries, whereas other ladybirds feed on fungi. One of these, Illeis galbula (Mulsant, 1850), from Australia, feeds on powdery mildew fungi. In New Zealand it is common on pumpkins and other cucurbits, plants that are commonly infected by powdery mildews. A plant feeding ladybird, hadda beetle (Epilachna vigintioctopunctata (Fabricius, 1775)) has recently established in Auckland. It feeds on plants in the Solanaceae (potato) family.

Lo PL 2000. Species abundance of ladybirds (Coleoptera: Coccinellidae) on citrus orchards in Northland, New Zealand, and a comparison of visual and manual methods of assessment. New Zealand Entomologist 23: 61-65.

Morales CF 1989. Saissetia oleae (Olivier), black scale (Homoptera: Coccidae). In: Cameron PJ, Hill RL, Bain J, Thomas WP ed. A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No. 10. Wallingford, Oxon, UK, CAB International. Pp. 237-240.

Slipinski A, Boyd B 2006. Revision of the Australian Coccinellidae (Coccinellidae). Part 6. Tribe Chilocorini. Annales Zoologici (Warszawa) 56(2): 265-304.

Slipinski A, Hastings A, Boyd B 2007. Ladybirds of Australia. www.ento.csiro.au/biology/ladybirds/ladybirds.htm

Valentine EW 1967. A list of the hosts of entomophagous insects of New Zealand. New Zealand Journal of Science 10(4): 1100-1209.

Alan Flynn for information about the biology of the ladybird.

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

1 November 2018. NA Martin. Changed symbol used for apostrophes.

1 August 2017. NA Martin. Prey table updated. Photo of feeding larva added.