Frequently, a cargo which is packed in an apparently uninfested state is found to be infested when the container is unpacked. The reason for this is that seeds, legumes and the like contain eggs which develop during the voyage. This is known as hidden or internal infestation.
Infestation can be recognized from:
Figure 64: Green peas. The arrows indicate peas infested by the pea beetle (Bruchus pisorum). |
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In the case of bagged goods, the bag seams are particularly sought out by the larvae of the khapra beetle and of the cadelle beetle and by some other kinds of beetle.
Indicators for recognizing the most important species:
- Pin head-sized round holes in infested granular goods are indicative of drugstore beetles.
- Round holes and irregular, eaten-away pits indicate granary weevils and the like.
- Grains stuck together with gossamer threads, often with lumps of excrement, are indicative of moths.
- Grey dust on and between goods and a honey-like odor are indicative of mites.
- Milled products which have lumps held together by gossamer threads are infested by moths.
- If they have pea-sized, often somewhat elongate lumps (egg cases) with larvae or pupae, the drugstore beetle is responsible.
- Fur beetles can be recognized by the roundish, closely spaced eaten-away areas. There are no traces of gossamer threads.
- Cereals with an increasing temperature or a musty odor may be infested by granary weevils, rice weevils, flour beetles or other species of beetles. In this case, the level of infestation is then relatively high.
- Holes or crumbly excrement on dried fruit are indicative of sap beetles.
- Legumes with small round windows only covered by the seed coat contain bean weevils and the like.
- Round "exit holes" without a lid, on the other hand, are indicative of drugstore beetles and lesser grain borers.