Do spider beetles lay eggs in grain?

Do spider beetles lay eggs in grain?

Yes, this is their primary method of reproduction. Females lay eggs directly on the grain surface, in packaging folds, or in crevices. The eggs are very small (less than 0.5 mm), similar in color to grain, and nearly invisible to the naked eye.

Egg-laying characteristics

• Oviposition sites: grain surface, bag corners, fold gaps, container edges.
• Number of eggs: one female can lay dozens to over a hundred eggs.
• Egg appearance: oval, milky white, smaller than a pinhead.
• Incubation period: at warm temperatures (25-30°C), about 7-10 days.

What to do when adults are found

Once you see adult spider beetles crawling in grain bins or cabinets, it is almost certain that eggs and larvae are already present:

1. Empty the entire bag of grain and inspect carefully for tiny white larvae.
2. Discard heavily infested grain in sealed bags.
3. For seemingly uninfested grain, freeze at -18°C for 48 hours to kill any hidden eggs.
4. Thoroughly clean the grain cabinet and treat crevices with food-grade diatomaceous earth.
5. From then on, store all grain in airtight containers.