(1) The methods of breeding larvae of Capnodis are described.

(2) A description of the larva and of its methods of locomotion is given.

(3) A study of the reaction of the larva to external stimuli is presented. It is pointed out that phototropic or geotropic reactions have no influence on the activity of the larva and that it is guided to its food through stereotactic and chemotropic reactions.

(4) The larva can detect roots or twigs from a distance of about 40 cm., and it can distinguish between the odour of various plants.

(5) Of various fruit trees, the odour of stone fruit was most attractive, and of these, almond comes first and apricots second.

(6) After the larva has located the root, and moulted, the sense of smell weakens gradually until it disappears. A comparative morphological examination of the antennae of neonate and mature larvae shows the olfactory organs are not present in the latter, while distinctly developed in the former.

(7) The larva feeds on the bark, tearing off minute particles, which it chews and finally discards.

(8) The tearing off of the fibres is facilitated by a fluid secreted from the mouth of the larva which softens the wood.

(9) Physiological tests show this fluid to contain a cellulose, a pectinase and an amylase.

(10) Development from hatching to pupation at 33° C. lasts about 60 days, at 27° C. about 100 days.

(11) From empiric data it is apparent that the threshold of development is about 18° C.

(12) From measurements and calculations according to the law of Dyar, the larva must moult at least nine times before pupating.

(13) The larvae resist temperatures above 42° C. for eight hours, but die after a few days in such temperatures.

(14) Practical considerations for the fruit grower based upon this study are presented.