THE IMPORTED PINE SAWFLY. 
19 
Table 11. — Experiments showing the results accompanying the forced use of certain 
species of pine as hosts by Diprion simile. 
Species and serial number of host tree. 
Parent 
females. 
Eggs. 
Larva? . 
Cocoons. 
Adults. 
Pinus sylvestris: 
Tree 1 
2 
3 
1 
1 
1 
2 
1 
3 
2 
1 
Tree 2 
9 
»N9 
79 
53 
27 
68 
3 
2 
21 
Trees 6 and 3 
48 
43 
18 
"X 
9 
Trees 15 and 16 
Trees 17 and 2 
2 
3 
2 
Trees 18 and 19 
1 
Tree 20 
Tree 21 
9 
3 2 
1 
Tree 29 
Tree 30 
6 
5 4 
Pinus austriaca: 
Tree 1 
Tree 2 
26 
5 


9 
13 
29 
Pinus strobus: 
Tree 16 
2 
6 
1 N= needles in which eggs have been deposited but the number of eggs not counted. 
* x= number not counted. 
Britton and Zappe, 10 in their paper on this species, give the follow- 
ing list, in which the pines are arranged "according to the preference 
shown by the sawflies in nature and to the largest number of sawilies 
reaching maturity'' in their host-plant experiments: 
Pinus excelsa Wall. Bhotan pine 
Pinus cembra Linn. Stone pine 
Pinus flexilis James. Limber pine 
Pinus strobus Linn. White pine 
Pinus koraunsis Sieb. & Zucc. Korean pine. 
Pinus montana Du Roi. Mugho pine 
Pinus densiflora Sieb. & Zucc. Japanese red pine. 
Pinus resinosa Ait. Red pine 
Pinus sylvestris Linn. Scotch pine 
Pinus ponderosa Dougl. Bull pine 
Pinus laricio Poir. var. austriaca Endl. Austrian 
pine 
Five-needled pines. 
>Two-needled pines. 
Pinus rigida Mill. Pitch pine Three-needled pine. 
This list shows that Diprion simile has a decided preference for 
the five-needled and the softer two-needled pines. A comparison 
of this list with the writer's experiments shows an agreement as to 
the preference for the five-needled pines and the apparent lack of 
suitability and attraction possessed by P. laricio, P. austriaca, 
and P, ponderosa, but a disagreement regarding P. sylvestris, which 
was a favored tree and capable of carrying the species from egg to 
adult in the writer's cages, while, along with P. jyonderosa and P. 
laricio variety austriaca, it was almost immune to infestation in the 
experiments of Britton and Zappe. 
From these data it seems reasonable to suppose that Diprion simile 
is capable of utilizing several of our American pines as hosts and 
therefore may succeed in establishing itself in the forests of the United 
n> Britton, W. E., and Zappe, M. P. Op. cit., p. 27S 
