Summer Activities

Broom gall mites (Aceria genistae) 

• Check for galls, which look like deformed lumps and range in size from 5 to 30 mm across. Very heavy galling, leading to the death of bushes, has been observed at some sites.
• Harvesting of galls is best undertaken from late spring to early summer,when predatory mites are less abundant. Aim to shift at least 50 galls to each site and tie them on to plants so the tiny mites can move across. 

Giant reed gall wasp (Tetramesa romana) 

• Check release sites for swellings on the stems caused by the gall wasps. These look like small corn cobs on large, vigorous stems, or like broadened, deformed shoot tips when side shoots are attacked. The galls often have small, circular exit holes made by emerging wasps. 
• It will probably be too soon to consider harvesting and redistribution if you do see evidence of the gall wasp establishing. 

Green thistle beetles (Cassida rubiginosa) 

• December is often when green thistle beetle activity is at its peak. Look for adult beetles, which are 6–7.5 mm long and green, so they are well camouflaged. 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. 
• If you find good numbers, use a garden leaf vacuum machine to shift at least 100 adults to new sites. 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. 

Honshu white admiral (Limentitis glorifica) 

• Look for the adult butterflies from late spring. Look also for pale yellow eggs laid singly on the upper and lower surfaces of the leaves, and for the caterpillars. When small, the caterpillars are brown and found at the tips of leaves, where they construct pontoon-like extensions to the mid-rib. As they grow, the caterpillars turn green with spiky, brown, horn-like protrusions. 
• Unless you find lots of caterpillars, don’t consider harvesting and redistribution activities. You will need to aim to shift at least 1,000 caterpillars to start new sites. The butterflies are strong fliers and are likely to disperse quite rapidly without any assistance.  

Moth plant beetle (Freudeita cupripennis)

• This beetle has established in the Bay of Plenty, Waikato, and Northland. Look for adult beetles on the foliage and stems of moth plant. The adults are about 10mm long with metallic, orangey-red elytra (wings) and a black head, thorax and legs. The larvae feed on the roots of moth plant so you won’t find them easily.
• The beetles can be harvested if you find them in good numbers. Aim to shift at least 100 beetles to sites that are not yet infested with the beetle.

Tradescantia yellow leaf spot (Kordyana brasiliensis) 

• Look for the distinctive yellow spots on the upper surface of the leaves with corresponding white spots underneath, especially after wet, humid weather. 
• The fungus is likely to disperse readily via spores on air currents. If human-assisted distribution is necessary, you will need permission from MPI to propagate and transport tradescantia plants. These plants can then be put out at sites where the fungus is present until they show signs of infection, and then planted out at new sites. 

Tutsan beetle (Chrysolina abchasica) 

• The best time to look for this agent is spring through to mid-summer. Look for leaves with notched edges or whole leaves that have been eaten away. The iridescent purple adults are around 10−15 mm in size, but they spend most of the day hiding away so the damage may be easier to spot. Look also for the creamy-coloured larvae, which are often on the undersides of the leaves. They turn bright green just before they pupate. 
• It will be too soon to consider harvesting and redistribution if you do find the beetles.

Tutsan moth (Lathronympha strigana) 

• 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 fruits infested with the larvae.
• It will be too soon to consider harvesting and redistribution if you do find the moths.

National Assessment Protocol 

For those taking part in the National Assessment Protocol, summer 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: https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/