PAN-PACIFIC ENTOMOLOGIST 
Vol. 55, No. 1, p. 72 
SCIENTIFIC NOTE 
FOOD PREFERENCES IN REARED WIRE WORMS CONODERUS 
EXSUL (SHARP) (COLEOPTERA: ELATERIDAE) 
The problem of rearing introduced species of insects becomes difficult 
when their food preferences are unknown. Such was the case with the wire- 
worm Conoderus exsul (Sharp) which was originally described from New 
Zealand. Studies of the food preferences of Limonius californicus (Mann.), 
(Stone, 1941, Life history of the Sugar-Beet wire worm in Southern Califor¬ 
nia, U.S.D.A. Tech. Bull. 744) showed that corn and wheat were superior 
to lima beans, in that more larvae pupated during the second year of their 
life cycle. Weights of corn or wheat fed larvae and subsequent adults were 
generally heavier than those reared on lima beans. 
The effect of different foods on the rate of development of the wireworm 
C. exsul was determined by individually confining larvae which hatched on 
March 25, 1977, in 2 oz salve cans. They were fed an excess of each food 
bi-weekly, at which time the soil was also changed. The foods were softened 
by soaking in water overnight. Twenty larvae were involved in each test. 
As indicated in Table 1, wheat was superior to the other foods, since 
Table 1. Effect of different foods on rate of development of the wireworm Conoderus exsul 
Sharp, Riverside, Cal. 1977-78. 
Days to complete larval period 
Rec¬ 
ords 
(No.) 
1977 
1978 
Mean 
Min. 
Max. 
Mean 
(No.) 
Min. 
Max. 
Wheat 
11 
144 
181 
156 
8 
275 
323 
300 
Corn 
6 
117 
165 
147 
13 
269 
366 
301 
Lima bean 
6 
130 
177 
160 
11 
293 
386 
316 
more larvae matured the first year, and there was less mortality. Corn and 
beans yielded fewer pupations the first year. Bean seed appeared more 
susceptible to rot and perhaps less palatable. Apparently the larvae of this 
species can exist on many kinds of food as it has already been recorded 
from 14 counties in California and from various localities in Arizona. 
The earliest pupation in the same year occurred July 21 and the latest 
September 22. Pupation the second year began December 19 and terminated 
April 15. Under favorable food conditions a sizeable number of this species 
may complete development in one year, which could account for its rapid 
spread. 
M. W. Stone, 131 Sir Damas Dr., Riverside, CA, 92507. 
