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• Issue 81 »
• Spring Activities

Spring Activities

Fruits infested with Darwin’s barberry weevil.

Broom leaf beetles (Gonioctena olivacea)

• Look for beetles by beating plants over a tray. The adults are 2–5 mm long and goldish-brown (females) through to orangey-red (males), with stripes on their backs. Look also
  for greyish-brown larvae, which may also be seen feeding on leaves and shoot tips.
• The beetles can be harvested if you find them in good numbers. Aim to shift at least 300 beetles to sites that are not yet infested with gall mites.

Broom shoot moth (Agonopterix assimilella)

• Late spring is the best time to check release sites. Look for the caterpillars’ feeding shelters made by webbing twigs together. Small caterpillars are dark reddish-brown and turn dark green as they get older. We are unsure if this moth has managed to successfully establish in New Zealand, so we will be interested to hear if you find any sign of the caterpillars.
• We would not expect you to be able to begin harvesting and redistribution just yet.

Darwin’s barberry weevil (Berberidicola exaratus)

• Although it is early days for checking release sites, later in the spring it might be worth beating some plants to see if any of the small (3−4 mm long), blackish adults can be found. Also examine the fruits for signs of puncturing.
• Since establishment is not yet confirmed, it will be too soon to consider harvesting and redistribution if you do find the weevils.

Green thistle beetles (Cassida rubiginosa)

• Look for adult beetles, which emerge on warm days towards the end of winter and feed on new thistle leaves, making round window holes. They are 6–7.5 mm long and green, so they camouflage quite well. Both the adults and the larvae make windows in the leaves. Larvae have a protective covering of old moulted skins and excrement. You may also see brownish clusters of eggs on the undersides of leaves.
• It should be possible to harvest beetles at many of the older sites. Use a garden leaf vacuum machine and aim to shift at least 100 adults from spring throughout summer and into autumn. Be careful to separate the beetles from other material collected, which may include pasture pests. Please let us know if you discover an outbreak of these beetles.

Lantana blister rust (Puccinia lantanae)

• Check sites where lantana plants infected with blister rust have been planted out, especially after a period of warm, wet weather. Signs of infection include leaf and stem chlorosis (yellowing), accompanied by large, dark pustules on the undersides of leaves and on the stems. Stunting, defoliation and die-back may also be apparent.
• Once established, this rust is likely to be readily dispersed by the wind. If redistribution efforts are needed, the best method is likely to involve placing small, potted lantana
  plants beneath infected ones and then planting these out at new sites once they have become infected. However, to propagate and distribute lantana in this manner an
  exemption from the Ministry for Primary Industries (MPI) will
  be required.

Lantana leaf rust (Prospodium tuberculatum)

• Check sites where the leaf rust has been released, especially after a period of warm, wet weather. Look for yellowing on the leaves, with corresponding brown pustules and spores, rather like small coffee granules. A hand lens may be needed to see the symptoms during early stages of infection. If the rust is well established then extensive defoliation may be obvious.
• Once established, this rust is likely to be readily dispersed by the wind. If redistribution efforts are needed, the best method will likely involve harvesting infected leaves, washing
  them in water to make a spore solution and then applying this to plants.

Privet lace bug (Leptoypha hospita )

• Although it is early days for privet lace bug, signs of their presence seem to be obvious quite soon following releases so it would definitely be worth checking the older release sites to confirm establishment. Examine the undersides of leaves for the adults and nymphs, especially leaves showing signs of bleaching.
• If large numbers are found, cut infested leaf material and put it in chilly bin or large paper rubbish bag, and tie or wedge this material into Chinese privet at new sites. Aim to shift at least 1,000 individuals to each new site.

Ragwort plume moth (Platyptilia isodactyla )

• October is the best time to check release sites for caterpillars, so look for plants with wilted or blackened or blemished shoots with holes and an accumulation of debris, frass or silken webbing. Pull back the leaves at the crown of damaged plants to look for large, hairy green larvae and pupae. Also check where the leaves join bolting stems for holes and frass. Don’t get confused by larvae of the blue stem borer (Patagoniodes farinaria), which look similar to plume moth larvae until they develop their distinctive bluish colouration.
• If the moth is present in good numbers, the best time to shift it around is in late spring. Dig up damaged plants, roots and all. Pupae may be in the surrounding soil so retain as much as possible. Shift at least 50–100 plants, but the more the better. Place one or two infested plants beside a healthy ragwort plant so that any caterpillars can crawl across.

Tradescantia leaf beetle (Neolema ogloblini )

• Look for the shiny metallic bronze adults or the larvae, which have a distinctive protective covering over their backs. Also look for notches in the edges of leaves caused by adult feeding, or leaves that have been skeletonised by larvae grazing off the green tissue.
• The beetles can be harvested if you find them in good numbers. Aim to collect and shift 100 beetles using a suction device or a small net.

Tradescantia stem beetle (Lema basicostata)

• The black knobbly adults can be difficult to see, so look for their feeding damage, which consists of elongated windows in the upper surfaces of leaves, or sometimes whole leaves consumed. Also look for stems showing signs of larval attack: brown, shrivelled or dead-looking.
• If you can find widespread damage you can begin harvesting. If it proves too difficult to collect 100 adults with a suction device, remove a quantity of the damaged material and put it in a wool pack or on a tarpaulin and wedge this into tradescantia at new sites (but make sure you have an exemption from Ministry for Primary Industries that allows you to do this).

Tradescantia tip beetle (Neolema abbreviata )

• Look for the adults, which are mostly black with yellow wing cases, and their feeding damage, which, like stem beetle damage, consists of elongated windows in the leaves. Larvae will be difficult to see inside the tips, but brown frass may be visible. When tips are in short supply, the slug-like larvae feed externally on the leaves.
• The beetles can be harvested if you find them in good numbers. Aim to collect and shift 100 beetles using a suction device or a small net.

Tutsan moth (Lathronympha strigana)

• Although the moths were only released last autumn, if you can’t wait, look for the small orange adults flying about flowering tutsan plants. They have a similar look and corkscrew flight pattern to the gorse pod moth (Cydia succedana). Look also for shoot tips that have been tied together and damaged by the larvae.
• It is too soon to consider harvesting and redistribution if you do find the moths.

Other agents

You might also need to check or distribute the following this spring:

• gorse soft shoot moth (Agonopterix ulicetella).
• gorse thrips (Sericothrips staphylinus).
• gorse colonial hard shoot moth (Pempelia genistella).

National Assessment Protocol

For those taking part in the National Assessment Protocol, spring is the appropriate time to check for establishment and/ or assess population damage levels for the species listed in the table below. You can find out more information about the protocol and instructions for each agent at: www.landcareresearch.co.nz/publications/books/biocontrol-of-weeds-book

Send any reports of interesting, new or unusual sightings to Lynley Hayes (hayesl@landcareresearch.co.nz, Ph 03 321 9694).