SINCE 1910, we have bred a continuous supply of the common stick insect (Carausius). These are lodged in a glass rectangular case 18½ in. × 9 in. × 15½ in. fitted with a movable glass front. Two glass vases holding ivy leaves in water furnish food and moisture for the insects. The debris is removed from the case once a fortnight, when fresh food and water are supplied. The eggs which lie about in the debris are picked out and placed in a small box which is kept inside the cage, so that they are subject to the same temperature and moisture conditions as the adults. There is always a mixed population of insects in the cage, ranging from newly hatched individuals to one year old adults.