LIFE-HISTORY STUDIES OF THE COLORADO POTATO 
BEETLE 
By PauunE M. Johnson, Scientific Assistant , and Anita M. Baixinger, formerly 
Preparatory Truck-Crop and Stored-Product Insect Investigations, Bureau of Ento¬ 
mology. 
INTRODUCTION 
The experiments on the life history of the Colorado potato beetle 
(Leptinotarsa decemlineata Say), the details of which follow, were sug¬ 
gested by Dr. F. H. Chittenden, in charge of Truck-Crop and Stored- 
Product Insect Investigations of the Bureau of Entomology, and were 
conducted under his direction. These studies were necessarily carried 
on indoors for the most part and under somewhat unnatural conditions. 
Had they been conducted out of doors, the probabilities are that in any 
well-kept field of potatoes (. Solatium tuberosum) the beetles would have 
passed through a period of estivation; and if the potatoes had been 
grown under weedy conditions, where the beetles had access to wild 
solanaceous plants, the third generation would have been produced. 
All experiments were performed in the District of Columbia during the 
season of 1914. The temperature during the period of the work was 
exceedingly high, with more than the normal rate of humidity. 
GENERATION EXPERIMENTS 
The overwintered beetles of this species made their first appearance 
after hibernation on April 29 on Solarium jasminoides , an ornamental 
plant growing in the insectary garden. Beetles were collected and pairs 
isolated in jars for experimental purposes. After feeding foir a few days 
the females began depositing their characteristic orange-colored eggs (PI. 
LXIII, fig. 1) in masses on the underside of the leaves near the tips. 
The egg masses averaged from 35 to 45 eggs each, except in two cases 
observed, in which as many as 70 and 72 eggs, respectively, were counted. 
When the potato plants first emerged from the ground, the beetles showed 
a decided preference for them, deserting the foliage of 5 . jasminoides for 
the more tender leaves of the potato. 
The fecundity of single females, under the conditions described, is 
shown in Tables I to VIII. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
ci 
(917) 
Vol. V, No. 30 
Feb. 14,1916 
X - 34 
