An experiment was designed to ascertain the maximum yield of adults of the Cigarette Beetle, Lasioderma serricorne (F.) that could be reared from a given quantity of foodstuff. Equal numbers of eggs of this species were added to batches of tubes containing different weights of wheatfeed, and the resulting adults were removed, counted and weighed.
The weights of wheatfeed had been chosen so that in some of the batches of tubes it would not be completely exploited. When emergence of adults was complete, further numbers of eggs, which were calculated to produce approximately the number of larvae necessary to complete the process in each batch of tubes, were then added, and the resulting adults again removed, counted and weighed.
The maximum biomass (wet weight) of adults of L. serricorne which could be reared from egg to adult per gramme of wheatfeed at 25°C. and 70 per cent. relative humidity was found to be 0.214 g. (108 to 129 specimens, all more or less undersized, and many with a retarded rate of development, compared with insects given ample food). In addition to the 21 per cent, of the food converted into adult insects, another 27 per cent. by weight of the original foodstuff was lost, presumably as water and carbon dioxide, leaving just over 50 per cent. undigested residue, most of which was faecal matter that would have passed through the insects at least once.
The yield of insects per g. loss of weight of the foodstuff was 0.46 g. (wet weights), which is very close to the corresponding figures calculated from the results of Fraenkel & Blewett for Dermestes maculatus Deg., Tribolium confusum Duv. and Ephestia Kuehniella Zell. on various foods, but three times as great as the corresponding figure calculated from Richards' results for Calandra granaria (L.) in wheat.
There was evidence suggesting that a truly maximal yield (slightly greater than in these experiments) might be attained by adding an optimal number of eggs to the food at the start, instead of adding a second population to an incompletely exploited food supply.