Many infections are known to start around crotches, and we speak
of them as crotch infections. The eggs of the bast miner are laid
near crotches and the newly hatched larvas may make entrance holes
sufficiently large to allow spores of blight to enter. Here again
the bast miner may be responsible, and if such proves to be a fact,
this insect would be the indirect cause of 90 per cent. instead of 50
per cent. of the infection on smooth bark trees. All other insects
mentioned as making wounds, with perhaps the exception of the tree
hoppers, are local or else the number of wounds is not appreciable;
but in the case of the bast miner, the insect is found wherever the
chestnut grows.