HYMENOPTERA. 



25 



the tip itself ; the instrument being sometimes three times the length of the entire 

 body. All the species of the genus are much alike in general appearance, the 

 smaller kinds being parasitic on small larvae, and the larger on those of superior 

 They may be seen flying about in woods in summer, in search of the wood- 



size. 



1, Ichneumon pisorius, male, and empty pupa of pine hawk-moth, whence the parasite has emerged ; 2, Cryptus 

 tarsoleucus, male ; 3, Mesostenus gladiator, female ; 4, Ephialtes manifestator, male and female, the latter 

 laying her eggs. (Nat. size.) 



boring larvae in whose bodies they lay their eggs. With intelligent agility the 

 female hurries over the trunk, but by what sense she ultimately detects the 

 presence of a larva within, and directs the ovipositor straight down to the spot, it 

 is impossible to say ; sight can be of 

 no assistance, nor, one would judge, 

 can touch. Can the antennae be used, 

 as the divining rod is supposed to be 

 used in the search for water, when 

 commonsense methods have failed ? 

 Possibly, however, the sense of smell 

 assists, and thus the seemingly 

 miraculous becomes once more a 

 common-place. The females appar- 

 ently follow the borings of the larvae, 

 for it would be next to impossible 

 for them to penetrate the hard fibres 

 of the timber in which their victims 

 burrow. One of the commonest 

 members of the family, and one of 

 the largest English forms, is Pimpla instigator, which preys upon many species of 

 larvae, especially those so destructive both in gardens and the forests. The perfect 

 insect may be seen on tree-trunks, in woods and hedgerows, searching for larvae, 

 with its wings raised, ready for instant action. The illustration represents this 

 species attacking the larvae of the satin moth. 



Pimpla instigator, female to the left, stinging the larva of the 

 satin-moth. To the right is the moth, beneath it the 

 pupa, from which emerges the adult, while the male of 

 the parasite is seen below. 



