- Penetration of the packaging used - insects with strong jaws (mandibles) launch a direct attack on the packaging material and chew away holes big enough for their body size. Since smooth surfaces offer little purchase, creases, seal seams, embossed patterns and other weak points are preferred. The lesser grain borer is particularly active.
- Invasion through faulty closures - insects with weak mandibles (moths) head for gaps in the packaging. The dried fruit moth is particularly active.