26 THE ENTOxMOLOGISt's kecokd. 



a specimen preserved in the first instar, in the interior of which are 

 unmistakable portions of mandibles of that instar. As no moulting had 

 occurred when this specimen was taken, they must have belonged to 

 an insect and not to a cast skin ; there was therefore cannibalism, but 

 whether the victim was attacked and killed with that object by its 

 mother or its brethren, or whether it died naturally or by accident, 

 cannot of course be decided. There was no obvious diminution in 

 numbers, so that this occurrence must have been an exceptional one. 



In the sixth instar the meso- and meta-thorax are produced in the 

 wing region, showing that the wings are developing. I have not 

 detected any external indication of wings in the fifth instar. The 

 sexeis can be distinguished in the fifth and sixth instars by external 

 chitinous structures apart from the internal organs, (but, so far as I 

 have examined the point, only after these chitinous structures are pre- 

 pared for microscopical examination), beneath the large terminal dorsal 

 plate. These are in the male apparently springing from its anterior 

 border and extending backwards, two (one on either side of the middle 

 line) short cylindrical processes, that appear to be internal, but the 

 chitinous covers are cast on moulting, so they must be external. In 

 the fifth instar these processes are very short, hardly longer than broad, 

 perhaps to be called conical rather than cylindrical, in the sixth instar 

 they are rather longer than half the length (antero-posterior) of the 

 last plate that they are under. ' (Plate, III., Figs. 11 and 12.) 



When the young earwigs had been some little time in their third 

 instar, I found one morning in the case of one of the nests I reared, 

 that all that remained of the mother earwig was her more or less dis- 

 articulated skeleton. She had been broken up and all the soft parts 

 eaten by her brood ; in the case of the other nest the mother lay dead 

 outside the nest, at the same stage of her brood ; these were plentiful 

 round their dead mother, and wandering about the jar. Two days 

 later the brood were found all collected in the nest, the remains of the 

 female disarticulated and cleaned out. Both these broods attended to 

 their own wants after this, apparently without difficulty and without 

 any mortality. 



The stage at which this occurred being the same in both instances, 

 led of course to the strong suspicion that the old earwig was not only 

 eaten, but first killed, by the children, as a customary proceeding. It 

 is, however, very possible that in both instances she really died of old 

 age. One may in any case, perhaps, assume that the j'oung earwigs, 

 numerous though they were, would have been helpless against her were 

 her strength and energy not very much diminished. There were no 

 indications that any of the brood had suffered in any defence she may 

 have made. 



That the mother dies as soon as her brood are large enough to find 

 their own living seems very probable, from the fact that in June young 

 earwigs may easily be found, but an imago is undiscoverable. This at 

 least was my experience in 1916, the first imago of the season being 

 found on July 14th. Exceptional individuals probably occur rarely, 

 and the actual dates would vary in different years. Later, imagines 

 are common, but examples in earlier instars get rarer and more rare, 

 and are probably unfortunate individuals that have not been able to 

 obtain enough nourishment to grow quickly, and may be also indi- 

 viduals of broods the mothers of which failed to make nests at the usual 



