The Pests And Diseases In Garden Leaves

Whatever you do, it is essential that you try as many methods as possible and do not give up in your attempts to keep this particularly unpleasant creature out of your garden, or at least keep its numbers at a low level. These seem to be one of the pests that occurs in plagues. They were a big problem in Victorian gardens, then vanished, to recur again recently. Probably not unconnected with the habits of the plant trade, as the adults cannot fly. What is eating these circular holes around the edges of the leaves on my plants? Several have been attacked, but the problem seems to be particularly bad on my wisteria and my roses.

The neat edges to the circular or elliptical holes is typical of damage by a leaf-cutting bee and makes it easy to distinguish this from the holes that other pests, such as caterpillars, slugs or vine weevils, might make in foliage It is the female bee who is responsible for removing the leaf sections and she does not in fact eat them, but uses them to construct little 'pods' into which she lays her eggs. I always think that these look rather like miniature cigars - they are made up of numerous leaf circles woven together. You may find them in the compost in old flowerpots or occasionally in rotten wood. A leaf-cutting bee will make lots of these structures and, when each one is finished, she fills it with a supply of pollen and nectar and then lays one egg in each, before closing it off with another circle of leaf.

You may have seen the bees around your garden and not recognized them for what they are, as they are very similar to honey bees, but have distinctly gingery-coloured hair beneath their abdomens - not the sort of thing you are going to notice easily! Although occasionally they can cause quite disfiguring damage, it is rarely that bad and is certainly of no significance as far as the plant's health is concerned, so I would not suggest that you do anything to attempt to control them. In any case, you should bear in mind that they are also useful pollinators.My mother has been looking after a colony of leaf-cutting bees for some years, because they make their 'tubes' down the insides of the plant pots in her greenhouse. I'm sure she wishes they would go away sometimes, but she cannot bring herself to get rid of them. They like the dry soil of pots holding cacti, succulents and dormant hippeastrum best.

It certainly sounds as if the larvae of the carrot fly have been responsible, as they carry out damage exactly as you described and attack all the plants you mentioned. An added problem is that, once the roots have been tunneled, they are very open to secondary infections, in particular both bacterial and fungal rots, which can mean that they will not store.