PASTOPOULOS AGRONOMICS
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Cossus cossus, the goat moth that hollows out fruit trees

Apricot Plum Sweet cherry
Probably the largest insect attacking fruit trees in Greece. Females have a wingspan of up to 100 mm; males are smaller. The moth is ash-grey to brown and on many hosts is an exact match for the bark of the trunk. The larva — the damaging stage — reaches 10 cm in length. It is pink on the back and flanks, with a black prothoracic plate. Take care: the larva can bite and the bite is painful. Do not handle it without gloves.

It completes one generation every two years. It overwinters inside the galleries it bores in the tree. Adults are on the wing from May to August and lay their eggs in cracks in the bark. The eggs — brownish and ridged — are usually laid in batches of 20–50. The larvae enter the bark and in their first year do not go beyond the cambium; they slow down over winter and, early the following spring, drive a gallery deep into the wood.

Control is extremely difficult, because the larvae are protected inside their galleries and because the window during which adults are present and laying eggs is very long. 
Where larvae are found in the trunks, the following steps should be taken at once.
   
   1) Scrape back the loose bark immediately, down to the point of attack — usually 6–15 cm.

2) Kill mechanically every larva that is visible, doing as little damage to the wood as possible.

3) Use a length of wire to reach and kill those still inside the galleries.

4) Where damage is severe, a trunk drench may be considered. The organophosphate named in the original Greek text (chlorpyrifos) has not been approved in the European Union since 2020 and must not be used. Any trunk treatment has to rely on a product currently authorised in Greece for the crop and the pest; the approvals are searchable at fyto.plantprotect.gr.

5) In Italy, cotton buds are dipped in an insecticide and pushed into the galleries.

6) Entomopathogenic nematodes are an alternative to a chemical treatment. The nematodes are suspended in water in a bottle and delivered through a fine tube into the holes in the trunk where the larva is working. 

7) Where the attack is in a scaffold limb rather than the trunk, remove the limb and burn it. 
Figure 2. Larva of Cossus cossus
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