Horizontal infestation

Some storage insects, like Angoumois grain moth and lesser grain borer infest grains right from the standing mature crop and their infestation migrates to storage through transportation, crop drying, threshing and grain drying during post-harvest operations. This infestation is termed as horizontal infestation.

For example, horizontal infestations occur when insects like S. cerealella and S. oryzae directly infest the grains of mature standing crop in paddy fields by laying eggs on the grains; the infestation migrates from fields to storage during post-harvest operations.
Horizontal infestation