174 



THE entomologist's RECORD. 



made from actual observations of my own, may be of some slight 

 interest, tending as they do to throw some little light on the time 

 which elapses between the laying and hatching periods. It will be 

 seen that the amount of variation is excessive, and this is not always 

 explained by reference to temperature, although this influence must be 

 very great. At present, the materials are not sufficient for theorising, 

 at least to me, but still one or two salient facts are worthy of record. 

 The most noteworthy is the duration or period in the egg state of 

 those which pass the winter without hatching, and it is curious to 

 remark that although some of these ova are deposited at least a 

 month earlier than others of the same species, yet the date of 

 hatching is practically the same. It is unnecessary to say that ova 

 can be hastened by being kept in a warm temperature, the fact being 

 so well known, but I am inclined to think that the very extraordinary 

 difference in the time of hatching of different broods of the same 

 species may be caused by the length of time which occurs in their 

 deposition ; that is to say, that the last portion of the batch laid by a 

 captured female hatches more rapidly, in proportion, than those first 

 deposited, but this is merely an idea. I have reared most of our 

 Geometr^e either from the ova or larva state, but fail to find 

 references among my notes to duration of time in the ova except 

 with regard to those enumerated below. The dates and the year 

 being given in every instance, it would be easy to compare the 

 average temperature of each period. Such a list may be in existence, 

 I dare say it is, but I have no time at present to work it out. So 

 many larvae are easily procured that rearing from the ova is not 

 always resorted to, but it is an interesting study which, however, is 

 often of little service from absence of notes and observations. 



