126 



INSECT TRANSFORMATIONS. 



Doors in egofs for the escape of the larvae, 

 a, egg of the louse {Pediculus hurnanus). b, egg of the penta- 

 toma. c, shell of a moth's egg found upon the dew-berry — all mag- 

 nified. 



nished with a convex lid, but with a lever of a horny 

 texture, and in the form of a cross-bow, for opening it, 

 the handle being fixed to the lower part of the egg- by 

 a membrane, and the bow part to the lid*. On the 

 leaf of a dew-berry (^Rubus ccesius) we found a 

 beautifully ribbed egg of some moth, which, having 

 been brought into our study, in January, 1830, was 

 hatched by the warmth, and exhibited an opening 

 similar to the elastic cocoon of the emperor-moth ; 

 each of the ribs having expanded to allow of the 

 escape of the caterpillar. 



The period at which the eggs of insects are hatched 

 after deposition depends mainly upon temperature; 

 for by keeping them in an ice-house in summer, the 

 hatching maybe retarded t, as it may be hastened 

 (witness the instance in the preceding paragraph) by 

 heat in winter; but there are many other circum- 

 stances unknown to us which often hasten or retard 

 the process. The eggs of the blow-fly {Muscavomi- 

 torid) are said to hatch within two hours |, while those 

 of several moths, and numerous other insects, remain 

 unhatched for six or nine months ; perhaps, in some 

 cases, even for one or more years. It is worthy of re- 



* Kirby and Spencc, iii. 104. f Reaumur, Mem. 



t Nouv. Diet. d'Hist. Nat. xii. 564. 



