WILLOW SAW-FLIES. 587 
Larva. — Head large, as wide as the body, rounded, pale yellowish ; eyes black, con- 
spicuous; legs pale whitish green ; eight pairs of abdominal legs ; abdomen closely 
rolled up when at rest like a Helix. All the segments finely wrinkled : the riflges 
bearing small flattened warts. Spiracles black. Body glaucous-green. Length 
18 mm . 
64 Galeruca decora Say. 
The most numerous and most dangerous of the enemies of the willow referred to 
by Professor Riley is, beyond question, the willow Galeruca (Galeruca decora Say), 
of which young larvae and imagos were met with everywhere on the leaves. The 
character of its injury and its natural history do not appear to differ from those of 
the imported elm leaf-beetle (G-. xanthomelama). Its eggs are a little larger, brighter 
colored, and less acuminate, and the young larvae of darker color, but not otherwise 
different. Full-grown larva? were not found early in June and only a few egg- 
clusters. 
60. Colaspis tristis Olivier. 
Next in importance, says Riley, comes Colaspis tristis, which in the imago state 
preferably feeds upon the very young, not yet fully developed, leaves. Its larva, 
which no doubt has subterranean habits, was not met with, and it probably feeds on 
the roots of some other plant. 
66. The willow dolerus. 
Dolerus arvensis Say. 
Order Hymenoptera.; family Tenthredixid.e. 
The following account of this insect is copied verbatim from Professor 
Forbes' third report on the injurious insects of Illinois: 
From one of the most intelligent and observant fruit growers of my acquaintance, 
I have heard from time to time of a " steel-blue fly" which clustered in spring upon 
the buds and blossoms of the pear, either eating them or blighting them and causing 
them to drop. On the 30th March he sent me specimens from his pear trees, and I 
found them to be the adults of the above two species which are known as willow saw- 
flies, — so called because their green, many-footed larvae feed on the leaves of willows. 
The evidence against these saw-flies lay in the fact that they were abundant and 
busy upon the opening buds and fresh blossoms of the pear and of some other trees, 
for many days in succession, and that the blossoms afterwards fell without setting 
fruit. Afterwards a similar but more positive charge against these insects appeared 
in the correspondence of the Western Rural, of Chicago, for May 17, 1884, as fol- 
lows: 
" Inclosed you will find a couple of bugs that are working on fruit trees here. 
They ruin many blossom buds by sucking the sap out of them, sometimes causing 
them to fall off just before opening. They make their appearance as soon as the 
trees begin to grow. You will notice there aro two colors of bugs— red and black. 
Is there any way to get rid of them ? Poison won't do it, for I have tried London pur- 
ple. They suck the sap mostly, although I think later in the season they eat the 
leaves some, but I am not sure of it. They work on pear worse than others." 
The first of these species, Dolerus arvensis, was originally described by Thomas Say 
in 1824, and the second, less common but still abundant, by Beauvois in 1805. 
Although the larvae of the former, at least, have been known for a long time to "feed 
upon the leaves of willow, they have not otherwise, so far as I am aware, been sus- 
pected of any injury to vegetation of economic importance, all the references to them 
in the literature of entomology being of a strictly technical character. From other 
insects occurring in similar situations, with which they are at all likely to be con- 
