Gloria Whelan, The Ambassador’s Wife, Ventura (CA), Vine Books, 1997, p. 134-135.

But I feel so vulnerable I nedd to build a shell around me like those caddis nymphs you told me about «  Harry had shown her how on the river bottom the caddis nymphs surrounded themselves with an armor of bits of stone. Harry’s voice was encouraging «  I suppose the caddis nymph could stay safely on the bottom of the river. Instead it shelds its shield and expoldes out of the water even though it only has twenty-four hours to live.