Im Speichel von Aphis pom: wurden fünf Aminosäuren und zwei nicht identifizierte ninhydrin‐positive Verbindungen papierchromatographisch nachgewiesen. Der Honigtau enthält zwanzig Aminosäuren und in besonders hoher Konzentration die Amide Asparagin und Glutamin. Herkunft und Bedeutung der Aminosäuren und Amide in diesen Ausscheidungsprodukten werden diskutiert.SummaryAMINO ACIDS IN SALIVA AND HONEYDEW OF APHIS POMI DEC, HOMOPTERARecently it has been suggested that amino acids play an important part in the relationship between plant sucking insects and their host plants. A method was therefore developed to collect uncontamiriated saliva from Aphis pomi and to estimate the amino acids in the saliva. To determine the accuracy of the method, the amino acids and amides on the honeydew produced by Aphis pomi were also estimated. Paper chromatography was used to estimate amides and amino acids.The amino acids alanine, glutamic acid, aspartic acid, valine, serine and two ninhydrin positive compounds which have not yet been identified were found in the saliva of Aphis pomi. Alanine and glutamic acid occurred in the greatest amounts. In contrast, the honeydew of Aphis pomi contains 20 amino acids and the amides asparagin and glutamine in especially high concentrations. Threonine, serine and glutamic acid are also found in high concentrations. In analyses of the saliva, no asparagin, glutamine or threonine could be found, though these substances are present in high concentrations in the honeydew.The significance of these facts is discussed. It is believed that amino acids in the saliva are breakdown products of the proteins in the food, and that they are circulated with the haemolymph to the salivary glands and then injected into the plant with the saliva.