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• Issue 83 »
• Autumn activities

Autumn activities

Hieracium gall midge damage

There are a few things you might want to fit in before winter.

Gall-forming agents

Autumn is the best time to check many gall-forming agents.

• Check Californian thistle gall fly (Urophora cardui) release sites for swollen deformities on the plants. Once these galls have browned off they can be harvested and moved to new sites (where grazing animals will not be an issue) using the same technique as above.
• Check broom gall mite (Aceria genistae) sites for signs of galling. Very heavy galling, leading to the death of bushes, has already been observed at some sites. Harvesting of galls is best undertaken from late spring to early summer, when predatory mites are less abundant.
• Check hieracium sites, and if you find large numbers of stolons galled by the hieracium gall wasp (Aulacidea subterminalis) you could harvest mature galls and release them at new sites. Look also for the range of deformities caused by the hieracium gall midge (Macrolabis pilosellae), but note that this agent is best redistributed by moving whole plants in the spring.
• Check nodding and Scotch thistle sites for gall flies (Urophora solstitialis and U. stylata). Look for fluffy or odd-looking flowerheads that feel lumpy and hard when squeezed. Collect infested flowerheads and put them in an onion- or wire-mesh bag. At new release sites hang the bags on fences, and over winter the galls will rot down, allowing adult flies to emerge in the spring.

Privet lace bug (Leptoypha hospita)

• If you find them in good numbers, aim to collect and shift 50–100 beetles using a suction device or a small net.
• Check for establishment by examining 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. 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.

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. Autumn Activities * If you can find widespread damage you can begin harvesting. If it proves too difficult to collect 50–100 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 MPI that allows you to do this).

Tradescantia tip beetle (Neolema abbreviata)

• If you find them in good numbers, aim to collect and shift 50–100 beetles using a suction device or a small net.
• 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.

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

Woolly nightshade lace bug (Gargaphia decoris)

• Check release sites by examining the undersides of leaves for the adults and nymphs, especially leaves showing signs of bleaching or black spotting around the margins.
• It is probably best to leave any harvesting until spring.

National Assessment Protocol

For those taking part in the National Assessment Protocol, autumn 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-ofweeds- book