Chapter XL 
INSECTS INJURIOUS TO THE WILLOW. 
Salix of different species. 
The willows harbor a very large insect population, and form the 
original food-plant of a number of the species at present living at the 
expense of our fruit trees. 
The number of species in Europe which live upon the willow 
is said by Kaltenbach to amount to 396. Of this number 94 are Cole- 
optera, 214 are Lepidoptera, of Hymenoptera there are 40 species, all 
of them saw-flies eating the leaves ; of flies (Diptera) there are 21 
species, all with three exceptions gall-flies (Cecidomyiae), while the re- 
mainder consists of Hemiptera, of which 27 kinds are enumerated, 
nearly all of these being Aphids and bark lice. 
It is to be observed that in Europe, as in this country, the number 
of borers is rather small, willows perhaps ordinarily not being exposed 
to their attacks, though this may be the result of imperfect observa- 
tion. Out of 94 kinds of beetles Kaltenbach enumerates about 12 
Cerambycida? or wood-borers, and only two or three bark-borers, while 
the greater number of the beetles he enumerates are leaf-beetles. In- 
deed, the large number of leaf-beetles and saw-flies which prey upon 
the foliage of willows, both in the old and new World, is a noteworthy 
fact. 
The number of species of willow insects we enumerate amounts to 
186, and there is little doubt but that the number will be greatly in- 
creased by future observations. 
AFFECTING THE TRUNK. 
1. Xylotrechus annosus (Say). 
In the month of April Mr. Ooquillett cut down a willow tree and di- 
vided it up into " sled-lengths," when no traces of borers could be 
seen ; but early in March of the following year, while cutting this wood 
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