IRREGULARITY OF INSECTS, AND UTILITY OF CALENDARS. 271 



cases, pretty accurately indicate the regular time of appearance. Every 

 naturalist I think must find it desirable to possess some calendar, to 

 point out to him the times at which he may expect to find the objects 

 of his research ; but when he finds in it so many inaccuracies, it is more 

 calculated to mislead than to assist him, and, consequently, the only 

 method which remains is for him to compile a calendar expressly for his 

 own neighbourhood, founded upon a series of accurate observations made 

 therein. He will find, however,that even in his own neighbourhood irre- 

 gularities occur, thus, perhaps, he may know that a species of insect is 

 found in one field long before it appears in another. Should this be the 

 case, he must search for the causes, and perhaps he will find that the 

 one field is damp and the other dry, or its aspect is shaded, while the 

 other is exposed to the sun, or more probably that the soil of the one 

 differs from that of the other. Whatever observations he may make, 

 and to whatever conclusions he may arrive as explanatory of the causes, 

 he should duly register in his note-book, and having a map of all the 

 fields round his neighbourhood, each of which is numbered thereon, the 

 differences observable in their soils, &c., may be also numbered so as to 

 correspond to them, and better to impress them upon his own memory. 

 Such a plan of proceeding will not only be serviceable in explaining 

 these irregularities, but will often be useful in pointing out certain 

 insects which may naturally frequent particular soils. Having done 

 this I would next advise him to bring from each field samples of the 

 soil, and to experiment upon their warmth and adaptation for evolving 

 and perfecting insect embryos. Such samples might be emptied sepa- 

 rately into flower-pots, placed at the side of one another, and all in the 

 same situation equally exposed to the open air, and in these embryos 

 of the same species being buried equally deep on the same day, by care- 

 fully watching for the time of the insect coming forth, calculations 

 could be easily made upon the time one soil took to hatch them to what 

 another did, and consequently he might expect with greater certainty 

 every succeeding year, when to find his insects in those fields from which 

 he took his samples of soil. To illustrate this more clearly, let us sup- 

 pose that he experiments upon the soil of three different fields, and 

 places them separately in the same number of flower-pots, the first of 

 which contains a chalky soil, the second common earth mixed with ma- 

 nure, the third damp marshy earth. Having adopted the manner of 

 experimenting as above laid down, each pot we will suppose to contain 

 chrysalides of the same age and species, and covered over with a piece 

 of coarse gauze to prevent the escape of the perfect insects when they 



