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When starting a crop there are generally few spiders present in the greenhouse, spiderwebs facilitate the Aphidoletes aphidimyza adults to mate If the Aphidoteles can't find a web there will possibly be less mating resulting in fewer egg deposits.  The solution is to apply a spider web yourself on the bucket in which they are deployed or to apply spiders in the crop.

Aphidoletes aphidimyza is active at night and sets its eggs at a minimum temperature of 12°C. The higher the temperature the better the egg deposits. During the daytime larvae develop best at a temperature of around 23°C.

When a plant is attacked by aphids it secretes chemical signals that attract natural enemies of the aphid. These signal substances are better dispersed through the greenhouse in warm air. At a lower temperature Aphidoletes has much more difficulty in detecting aphids and locating their prey.  

The humidity in this period of the year is generally low due to a young and open crop meaning dewdrops are present in the crop to a lesser extent. These dewdrops are essential for hatching gall midges because they drink from them. If the gall midges do not drink they can die within a few hours. Solution: Place a wet cloth in a bucket or place a piece of moist floral foam with 10% sugar water in the place where you introduce the material. 

Air humidity is also important for egg deposits. Aphidoletes aphidimyza prefers the leaves at the bottom of the plant because the conditions are the most moist and dark here.

In many new crops foil is placed on the ground for hygiene reasons. However, this has a negative impact on the development of Aphidoletes aphidimyza. The larvae can only pupate in the ground. If the larvae end up on the foil and cannot reach the ground they will die. As a grower you can do little about this but be aware of it. Soil temperature is also low during this period of the year. Keep in mind that the pupation process takes longer, so it takes longer for a new generation of gall midges to emerge.

The final point of attention is not related to the weather but is therefore no less important: disperse the material. APHIDOcontrol from the supplier Agrobio is supplied in bottles with vermiculite as a carrier. For some products, you only have to turn the cap of the bottle and then put it in the crop but with APHIDOcontrol this is not the case. This material must be scattered. If you don't do that some of the gall midges won't get through the vermiculite and will therefore stay behind in the bottle. 

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