128 Bulletin de la Société Royale Entomologiquc d'Egypte 
after oviposit i on had begun w as the cause of irre¬ 
gularity. The only evidence I have against this in¬ 
terpretation is that supplied by N° 887 in table VIII ‘b’ 
and bv N° ito. The intervals between the 8 ess- 
cases made by the latter before copulation are re¬ 
corded in table X, they are like the first 5 of N° 837 , 
verv irregular without any marked tendency towards 
compensating one-another. N° 119 made its 8th egg 
case on the 9th of October, on the 17th a male caught 
outside was placed in the same cage and copulation 
was observed on the next day and again on the 4th 
and 5 th of November. The pair continued to live to 
gether until the 20th of January 1917 when the fe¬ 
male died; three days later the male died. We have 
no records of fertilized egg-cases laid during this pe¬ 
riod with which the intervals could he compared, 
but the increase in the length of the interval after 
copulation — in this case for the first time as well 
as for the second — is followed by a decrease which 
— in the first case at least — is most significant. 
N° 337 made its 6 th egg-case on the 22nd of 
June 1917. Three days later a male was placed in the 
same cage and pairing took place before the laying 
of the 7th egg-case on the 3 oth. The male w^as eaten 
on the 8th of July. The average of the first two inter¬ 
vals after copulation is 6, which is the same length 
as each of the last three intervals. 
We have seen in the last, section that, the period 
between, the final moult and the first ov-iposition is 
longer in the case of unfertilized females than in that, 
of their married sisters. This postpones the date of 
laying of subsequent egg-cases,, in some cases very 
