The GARDENA gardening expert
The fact that you have an infestation every year, Mr. S., may possibly be that the animals (Yellow Gooseberry Sawfly, Nematus ribesii) live in the soil as larvae over the winter. The sawflies hatch the beginning of April and begin laying eggs on the underside of leaves, hidden inside shrubs. Therefore the suggestion of thinning out the plants with the aim of discovering an infestation early on. The yellow Gooseberry Sawfly can manage up to four generations in one year.
There is a risk of confusing the Gooseberry Sawfly with the Magpie Moth (Abraxas grossulariata) which lays its eggs from July – August but in piles, not in rows as with the Sawfly. The larvae can be distinguished as follows: Nematus has six dark legs on the front end, Abraxas has additional back legs which are typical for the moth and are also dark. Abraxas has a yellow vertical stripe as well.
Both types can be chemically combated with an insecticide for biting and eating insects for example, with the nature-friendly agent Spruzit Schädlingsfall (by Neudorff). Another alternative is that it should be possible to cover the crown of your gooseberry stems beginning with the flowering season until the middle of August with an insect-protective netting.