Tuan Cao; (inset) Joseph Deas

ScienceShot: A Shield Made of Eggs

Beetles and Lego castle builders both know that stacking is the key to a strong fortress. The seed beetle (Mimosestes amicus) plops its shiny eggs one on top of the other to protect the bottommost eggs from parasitic wasps, which drill inside to the yolk and lay their own offspring. The strategy works: lab studies show that shielded eggs get cannibalized much less often, researchers report online this week in the Proceedings of the Royal Society B. Wasps, instead, tend to go for the top-most eggs. And they're welcome to them: As far as the beetles are concerned, these outer shield eggs are duds, good only, perhaps, for protection. In fact, the beetles pump so few nutrients into these outer eggs that many of the wasps infesting them wind up starving. Try building a Lego castle that can do that.

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