18 
BULLETIN 1182, U. S. DEPARTMENT OF AGRICULTURE. 
into which the following species of young pines had been trans- 
planted. 
Number of trees 
Species. placed in insectary. 
Pinus austriaca 2 
Pinus cembra 2 
Pinus divaricata 2 
Pinus flexilis 3 
Pinus laricio 4 
Pinus monticola 3 
mus monticoia 6 rim 
Twelve species and a total of forty-eight trees 
Number of trees 
Species. placed in insectary. 
Pinus ponderosa 5 
Pinus resinosa 3 
Pinus strobus 5 
Pinus sylvestris 15 
Pinus taeda 1 
Pinus virginiana 3 
In Table 10 the host trees are arranged according to the number 
of trees of each species that were chosen by the females for oviposi- 
tion and the suitability of these pines as hosts is indicated by the 
number of individuals of the sawfly that were able to develop through 
the various stages from egg to adult. 
Frequency of selection for oviposition has been considered a some- 
what better guide to the appeal of the various pines to the sawfly 
than the numbers of the different stages of the insect obtained. 
This is especially true where the number of adults obtained exceeds 
a third of the total number of larvae, since the larvae after hatching 
were cage-reared, and, although protected from parasites, doubtless 
experienced a number of difficulties due to handling and to their 
artificial surroundings. The species of pines believed most favorable 
for D. simile are therefore placed at the beginning of the table. 
Table 10. — Experiment to determine the host-plant preference exhibited by Diprion simile. 
Pinus sylvestris, trees 1, 20, and 29. 
strobus, trees 5 and 6 
cembra, tree 2 
virginiana, tree 14 
divaricata, tree 1 
monticola, tree 2 
flexilis, tree 2 
taeda, tree 9 
resinosa, trees 16 and 18 
austriaca, tree 2 
Number 
of trees 
of species 
Eggs. 
Larvae. 
chosen. 
3 
ix 
13 
2 
X 
36 
1 
X 
12 
1 
X 
21 
1 
X 
14 
1 
X 
10 
1 
X 
5 
1 
8 
5 
3? 

2 
«? 

1 
Cocoons. Adults. 
1 x= number not counted. 
2 27 larvae killed— rain. 
a ?= trees examined and no eggs found. Therefore, while, it is possible that eggs may have been over- 
looked, it is also possible that a larva dropping or knocked from another tree may have reached these; 
consequently these species can not be given full credit for choice. 
Table 11 gives a summary of experiments in which adults of 
Diprion simile were confined in cages on single young trees of certain 
species of pine. It shows in some degree the greater success attend- 
ing the use of Pinus sylvestris as a host for the sawfly. 
