Qualitative tests for the presence of amylase, invertase, maltase, lactase, cellulase, hemicellulases A and B, and proteinase in the digestive juices of wood-boring coleopterous larvae are described.

Fourteen species representing the families Scolytidae, Cerambycidae, Lyctidae, Bostrychidae and Anobiidae, have been investigated and their nutrition is discussed in terms of the enzymes found and present knowledge of the composition of wood.

It is concluded that three types of wood feeding may be distinguished, (i) larvae able to utilize only the cell contents and perhaps part of the polysaccharides which are intermediate in composition between starch and the hemicelluloses--Lyctidae and Bostrychidae, (ii) larvae able to utilize cell contents and the carbohydrates of the cell wall up to hemicelluloses, but excluding cellulose--Scolytidae (bark beetles), and (iii) larvae able to utilize cell contents and the carbohydrates of the cell wall including cellulose--Anobiidae and most Cerambycidae.

A proteinase is of general occurrence in the larval guts of wood-boring beetles.

Digestive enzymes were absent from the gut of hibernating larvae of Scolytus destructor.

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