In litter houses the manure builds up under the slats and this area is often relatively
inaccessible. The drinkers are often placed on the slats and unless there is very
good water control, drippage leads to wet manure and flies build up.
In the free range building above, if flies are not at a high level then it will
be possible to treat the area at the sides of the slats by applying the wasp infected pupas through the
slats. If flies are at a high level it might be necessary to also apply a larvicide
where the manure is wetter under the drinkers. Once the flies are reduced and the
wasps have some control then the larvicide can be reduced.
The wasps should be released where the fly pupa population is highest, this might
be around the edges or posts in a free range house, but might be over the entire
manure pile where the manure is removed mechanically.