A QUEER HOUSE BUILDER 105 
the leaf. One tribe which visits the scarlet and 
black-jack oaks have a decided hand in shaping 
the tree. Their nursery is in the wood of a 
branch. Outside this nursery is a great black 
knot deforming the whole limb; within is a mass 
of cells with a little worm living in each. One 
may easily sight dozens of such nurseries down in 
the wood-lot, and all but the initiated will pass 
them by totally unsuspecting their real character. 
“ One species of gall-fly attacks the rose¬ 
bushes, and works all sorts of wonders. For ex¬ 
ample, often on a smooth stemmed rose we find 
a queer wart or gall that is covered with thorns. 
Every part of the rose is affected by the various 
gall-flies which frequent it—root, stem, leaves, 
all are distorted with their greenish swellings, 
which turn to shades of red and yellow and finally 
to brown as the season advances. When fully 
matured the spiny rose gall just mentioned is as 
large as a cockleburr, but round in shape, and 
most thoroughly protected by its defensive armor 
of rigid thorns. Inside is a full-grown larva, per¬ 
haps one-sixth of an inch in length. The gall is 
now dead, but it serves the little footless, worm¬ 
like creature for shelter until spring, when an 
active little gall-fly emerges from the little 
‘ house ’ through a round hole which it has 
gnawed in one side. 
“ When you once get to looking for galls you 
