JULY. 187 



larvse, she inserted her ovipositor ; the poor grub when pricked 

 gave a violent wriggle, and this operation was repeated till all 

 had received the egg which would prove so fatal a deposit. 

 In these instances the larvse of the Ichneumon are solitary, 

 but in some species they are gregarious, the parent depo- 

 siting several eggs in the same caterpillar : this is the case 

 with the Ichneumon, Microgaster glomeratws, which preys 

 on the larvse of Pontia rapa, or Small White Butterfly. 

 These caterpillars, when full grown, creep up to the corner of 

 window-frames, or similar places, to undergo their change ; 

 but frequently, previous to this transformation, a great 

 number of small white grubs issue from them (causing, of 

 course, the death of the caterpillar) ; the little grubs imme- 

 diately enclose themselves in oval cocoons, attached round 

 their victims, looking like a mass of yellow silk. Some- 

 times the larvse remain within the caterpillar until it is in 

 the chrysalis state, when they come forth in their perfect 

 condition; this depends on the species of Ichneumon, as 

 well as on the growth of the caterpillar. It is a wonderful 

 fact that these little parasites never attack the vital parts 

 of the larvse (as this would destroy their supply of food), 

 until they have nearly attained their full size, when they at 

 last destroy the organs of life, and then piercing through 



