The walnut maggot is an easily recognizable dipteran: it is cream colored and often has black spots, transparent wings with dark bands.
Each female can lay up to 400 eggs, inside the nut shell that is already marked by the females themselves with an inhibitory pheromone (to ensure that other specimens do not deposit in the same nuts). When hatched, the eggs feed on the ball; the larvae ripen in 3-5 weeks: they cause the darkening of the hull which slowly covers all the fruit.
(Foto: Syrio - Opera propria, CC BY-SA 4.0 https://commons.wikimedia.org/w/index.php?curid=62204969)
After placing two 1.5V AA batteries (not included) in its battery compartment, insert the luminaire into its bracket inside one of the semispheres, then assemble the sphere.
Before applying the glue, wrap the sphere with a transparent plastic film (such as cling film, or two clear shower cups); then apply a suitable glue.
Suitable glues range from sprayable to brushable, specific for insects and tube glue (such as mouse glue), all of which are available in garden centres and specialised stores.
In the event of loss of adhesion, the glue can be reapplied several times.
In addition to using only glue, or glue and attractants on it, Sfera Trap™ can also support insecticides and pheromones.
Practical advice: Use disposable gloves in the preparation of the sphere and the various products used. To avoid damage from possible spillage of glue, place a protective sheet underneath the sphere, such as cardboard or paper. In the eventuality of glue spillages these can be removed using white spirit or turpentine.