A QUEER HOUSE BUILDER 
“ See here, Uncle John,” begged Tommy, 
“ please read this riddle for me. Grandmother 
says it is an oak apple; I knew that already. I’ve 
cut several open, and there’s nothing but a 
spongy growth inside. What makes them, and 
what good are they? ” 
“ Hmm! ” murmured Uncle John, reaching 
for the specimen. “ First, let me show you that 
your investigations were not complete enough.” 
With his knife he cut deftly into the “ apple,” 
and pushing aside the spongy matter disclosed a 
hard little kernel about the size of a pea. “ See! ” 
he said, “ here is a tenant. Inside this cradle is a 
little white grub, the child of one of the many 
insect foes of the oak. In the autumn the oak 
apple falls with the leaves, and lies safe and snug 
among them until spring, when the little grub 
that was comes forth transformed into a gall-fly 
like its mother. It is a small, dark-colored, four¬ 
winged fly, and, after a brief wedding journey, 
the female sets out to lay her eggs on the oak 
leaves just as her mother before her has done. 
“ Of all the queer eggs that of the gall-fly is 
the queerest! It is a slender little affair, with a 
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