The forewings of an adult apple ermine (Yponomeuta malinellus) are white with three rows of black dots along the wings; the hind wings are silver-grey. The wingspan of the moth is 18-20 mm. The moths hatch from pupae in the second half of July; their flight lasts for approximately a month and takes place in twilight, in windless conditions. During daytime, the moths remain immobile and unnoticed on the bottoms of leaves.

After the flight, female moths lay bundles consisting of 20-80 eggs on narrow branches. The bundles are covered with tiny shields with a diameter of 3-4 mm. The small larvae, hatching from the eggs in the autumn, overwinter under these shields. Starting from spring, the larvae feed on leaves and create cobweb nests from their secretions. They live in these nests in colonies, growing up to 18 mm in length over 30-40 days. The fully grown larvae are whitish-yellow or greyish-yellow with a distinctive row of spots on their backs. They pupate in the same cobweb nests. The pupae develop for 2-3 weeks and new moths hatch usually in the second half of July. Adult apple ermine (moth), larva and cobweb nest

Pheromone trap for the apple ermine

From time to time, gardens and orchards in Estonia face years in which the apple ermine is seen in large numbers. Although the larvae of the apple ermine (Yponomeuta malinellus) do not damage the fruit, they damage the leaves, exhausting the tree. If the pest is present in large numbers, the harvest decreases, not to mention the unpleasant appearance of the trees.
In spring, the tiny larvae that have survived the winter first feed on the pith of fresh leaves (inside the leaves), but they exit the leaves at around the time of blooming and start to create cobweb nests from their secretions, using more and more leaves of the apple tree to feed on. If the pest is present in large numbers, the entire foliage is destroyed and the tree might wither.
The apple ermine moths hatch from pupae in the second half of July; their flight lasts for approximately a month and takes place in twilight, usually in windless conditions. By using 2-3 apple ermine pheromone traps, you will be able to identify the presence of this pest in your garden and, based on the insects caught in the traps, estimate their numbers in your garden. By using more traps in the garden, the pests can be trapped out in order to avoid any further increase in their numbers.
The rubber capsules used in the pheromone traps are saturated with the fragrance secreted by female apple ermines – a pheromone substitute that attracts the male moths of the same species to enter the trap. The pheromones are non-toxic and the doses used (1 mg) are tiny and do not pollute the environment.

Assembly of the trap

The edges at the bottom of the trap are folded upwards.
The pair of gluey bases is pulled open and one gluey base is placed on the bottom, gluey side upwards.
The rubber pheromone capsule (dispenser) is placed in the centre of the gluey base.
Fasteners are pushed through the openings and used to fasten the trap to a branch.
The trap is hung as horizontally as possible on the southern or western outer branch of the apple tree in order to cover it from direct sunlight.
When using pheromone traps in order to monitor the pest, the traps are hung at a height of approximately 2 metres in order to make it possible to inspect them once a week.
For monitoring purposes, the trap is opened from the side, the insects are removed from the gluey base with a spatula or the edge of a knife, and the number of apple ermine in the trap is registered.
If it becomes apparent in the course of the inspection that the gluey base is dusty or filled with insects and refuse, it must be replaced.
If there are numerous pests in your garden – if the traps catch an average of 5-10 or even more moths per trap in a week – it is recommended to conduct insecticide spraying and continue monitoring the numbers of the apple ermine in order to decide whether spraying should be repeated.
It is recommended not to conduct insecticide spraying if the number of moths caught is below the spraying criterion. This will help you preserve nature and avoid needless expenses on insecticide.
We recommend hanging more traps in the garden (trapping out) in order to avoid any further increase in the numbers of the pest.
Trapping out adult apple ermines with pheromone traps is well suited for pest control in your own garden where it is not recommended to use insecticides at all, or if required, insecticides are used as little as possible.
For the purpose of pest control, a trap must be hung on every tree or one for every two saplings, and the traps must definitely be hung higher – at a height of 2-3 metres – as the pests mainly fly in the upper third of the treetop. After 3-4 weeks, the gluey bases of the traps have gathered plenty of dust, are covered with insects and refuse, and should certainly be replaced. If the flight lasts for a longer period (mainly depending on the weather), both the gluey base and the dispenser should be replaced in the second half of July.
If the spare capsule is not required, it can be stored in a cool place in sealed packaging and used next spring.

NB! The glue used on the base is very sticky and cannot be washed off with water. Regular petrol or white spirit may be used for cleaning hands; cooking oils and other substances are less efficient.

If the weather has not excessively damaged the casing of the trap, it may be used again next year, but only for the same insect species. In order to avoid a new increase in the numbers of the pest in the garden, you should continue using the traps.”