FURTHER NOTES ON THE EARWIG 177 



Further Notes on the Earwig. 



By T. A. CHAPMAN, M.D. . 



My notes on the Earwig in the PJntoiiiologist's Record of last 

 January left several points in some doubt, and suggested others for 

 investigation. I bred some earwigs last spring and report some of 

 my observations, although the results were not so complete as I wished 

 to make them. One rather curious difficulty I met with was, that 

 though the young earwigs and their parents usually live very amicably 

 together, two or three broods, that I wished to watch carefully, did 

 not do so, and made it difficult to follow their progress. It did not 

 appear that giving or withholding animal food could be assigned in 

 these cases as causing them to damage each other. 



In 1916, the nests I observed were each made by a female earwig, 

 but in most, but not all, of those in 1917 each nest was inhabited by a 

 pair, (J and J , of earwigs, I also found such a nest at large, and Mr. 

 Main sent me two pairs of earwigs taken from such nests. 



How this accords with the pairings seen in late autumn I don't 

 know, but doubt very much whether they were the same pairs. I 

 never observed a male licking over the eggs, but as he is present all 

 the time, and certainly assists later in the care of the young earwigs, 

 it seems very probable that he assists in this process also. 



The dates of latest survivors given below show that males sur- 

 vive as long as females. 



As to the young earwigs eating the remains of the mother, this 

 did not often occur, the young earwigs certainly do not occasion her 

 death, nor do they eat her remains when other food that pleases them 

 is abundant. It occurred in two cases that two females together occu- 

 pied one nest with the young brood. The insects were very clever in 

 hiding the entrances to their nests. I had six or seven earwigs in a 

 jat with a view of removing the surplus as soon as a nest was made, 

 but in several cases a second nest was made that I knew nothing of, 

 till the young earwigs appeared, and this sometimes caused a doubt to 

 be thrown on some of my records, so that I could not depend on 

 them. 



In one case a ^ and ? that had made no nest, and appeared to 

 be doing nothing, were observed m cop. on April 16th, and again on 

 May 5th. On the 16th May there was no sign of burrow or nest, but 

 a burrow was found on May 21st. On the 28th the J^ was dead and 

 the burrow ended in a nest containing eggs. The female died on 

 July 2nd. 



I expressed some considerable doubt as to whether I had correctly 

 observed the moultmg. I believe that the doubts were well founded, 

 and that there are only five, and not seven, instars, and that at each 

 moult the number of antennal joints is increased. The correlation of 

 antennal joints with instars being, 1st instar 8 joints ; 2nd instar 

 10 joints; 3rd instar 11 joints; 4th instar 12 joints; 5th instar 

 (imago) 14 joints. I verified this in counting the moulting in certain 

 selected specimens, and also by segregating some individuals with 10 

 and some with 11 joints, and finding that in every instance there was 

 an addition of joints after a moult, no specimen of 10 joints had only 

 10 after moulting, nor did one with 11 appear after the moult witn 

 less than 12. 



September 15th, 1917. 



