1940] Food Preferences of Colorado Potato Beetle 
43 
vations that the beetles maintain themselves indefinitely on 
potato. 
It thus appears that not only do the beetles evince a dif- 
ferential choice among various Solanums and other solana- 
ceous plants as was first clearly shown by Trouvelot, et al. 
(’33a) , but the choice of the beetles is not always compatible 
with the larval requirements in the way of food. Thus even 
if the beetles are unable to maintain themselves for more 
than a year or two on plants that they will quite willingly 
attack we may readily understand how the potato-beetle and 
similar insects fail to widen their range of food-plants even 
though the instincts of the adults may vary considerably in 
directions incompatible with larval food requirements. What 
happens in such cases is that a certain proportion of the 
population is doomed to extinction due to faulty instinct of 
the parents in selecting unsuitable food-plants. If the 
environmental resistance rates high or the “viscissitudes of 
life” are excessive, as is usually the case, this factor plays 
an important part in the economy of the insect, but in the 
case of pests of agricultural crops where this environmental 
resistance is lessened by an excessively increased food-supply 
it becomes of very minor importance. 
LITERATURE CITED. 
Feytaud, J. 
1923. Etude sur le Doryphore. Ann. Epiphyties, vol. 9, pp. 209-306. 
Mclndoo, N. E. 
1935. The Relative Attractiveness of Certain Solanaceous Plants to 
the Colorado Potato Beetle. Proc. Entom. Soc. Washington, 
vol. 37, pp. 36-42. 
Trouvelot, B. & Grison. 
1935. Variations de fecondite du Leptinotarsa clecemlineata avec les 
Solanum tuberiferes consommes par l’insecte. C. R. Acad. Sci., 
Paris, vol. 201, pp. 1053-55. 
Trouvelot, B., D. Lacotte, Dussy & Thenard. 
1933a. Observations sur les affinites trophiques existant entre les 
larves de Leptinotarsa decemlineata et les plantes de la famille 
des Solanees. C. R. Acad. Sci., Paris, vol. 197, pp. 273-275. 
1933b. Les qualites elementaires des plantes nourricieres du Leptino- 
tarsa decemlineata et leur influence sur le comportment de 
l’insecte. ibid., t.c., pp. 355-356. 
Trouvelot, B. & ,T. Thenard. 
1931. Remarques sur les elements des vegetaux contribuant a limiter 
on a empecher la pullulation du Leptinotarsa decemlineata 
Say, sur de nombreuses especes ou races vegetales. Rev. Path, 
veg. Entom. agric., vol. 18, pp. 277-285. 
