Aphidoletes is a gall midge that occurs in Europe, North America and Asia. Contrary to some other gall midge species, Aphidoletes does not cause damage by forming galls on leaves. The adult is about 2.5 mm long, with long legs and a slender body. Males have long antennae that are bent backwards and are covered with long hairs, while females have shorter, darker antennae.

Aphidoletes is mainly active at night. After sun set the female deposits her eggs in aphid colonies. The number of eggs depends on the climate and the nutrition the gall midge has had as a larva and as an adult, but it usually amounts up to more than hundred. After 2-3 days eggs hatch to larvae and almost immediately start sucking aphids empty around them. There are 3 larval stages. Initially the larva is transparent orange, but later on it turns, depending on its food, orange, red, brown or grey. After a life of 7-14 days (at 21°C or 69.8°F) as a larva, it pupates in the ground. It makes an oval, brown cocoon covered with sand grains, aphid skins and excrements. Seven to 14 days later an adult gall midge emerges.

Since the larva looks for its prey in the surrounging 6 cm of its birth place, the female gall midge prefers to deposit her eggs in sufficiently big aphid colonies. One larva needs minimum 5 aphids for its development, but it will kill more if there are more available. The larva first injects a poison in the aphid, which paralyses the aphid and dissolves its body contents in 10 minutes. Aphidoletes aphidimyza is known to eat at least 70 different aphid species. The adult feeds on honeydew. The adult life span is 7-10 days, but it might be shorter at lack of honeydew. Dry conditions also shorten life span. Mating ususally occurs after sunset or before sunrise or on a fresh and shady place low in the crop.

In nature the pupa enters diapause from end September till May (in temperate regions). In the greenhouse this diapause is interrupted by higher temperatures from early spring on.

The main benefit of Aphidoletes aphidimyza is its applicability on several crops on which any kind of aphid occurs. The gall midge can be introduced preventatively with an aphid parasite (Aphidius colemani, Aphidius ervi or Aphelinus abdominalis) at 0.1 Aphidoletes/m².

As soon as the first aphid colonies are detected or flying aphids are seen on yellow sticky plates (BUG SCAN®), Aphidoletes can be released curatively. Depending on the crop and the aphid species, 0.5-2 Aphidoletes/m² are weekly introduced. In hot spots, weekly introductions of 5-10 gall midges are recommended.

In soil cultures larvae can pupate in the ground and successive generations occur. In substrate cultures the pupae do not find appropriate sites for pupation and many die. Therefore, a biological balance with aphids is not possible in substrate cultures. Aphidoletes should here rather be considered as a temporary way to control developing aphid colonies (biological corrector).

For controlling further developed colonies, the ladybird Harmonia axyridis can be released in the hot spots, or the selective pesticide pirimicarb (Pirimor, ...) can be used.

Aphidoletes aphidimyza is supplied in units of 1000 pupae mixed with vermiculite. They are packed in plastic sprinkler bottles, by which the pupae can be introduced equally in the greenhouse.

Note: Several pesticides have a negative effect on Aphidoletes aphidimyza. Please be careful when controlling diseases and other pests. Consult Biobest's list of side-effects of pesticides on beneficial organisms.

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