1 50 The Field Naturalist's Quarterly May 



Linnaeus, Forster, Fabricius, &c. — before this impasse was 

 realised, there was no lack of students of this family, but 

 since Gravenhorst exhibited in 1829 the great number of 

 species that were then known to exist, their microscopic dis- 

 tinctions, and the innumerable errors into which the first 

 nomenclators had fallen, entomologists have become ex- 

 tremely chary of tackling so intricate and enravelled a skein. 

 Consequently but few works, compared with those upon 

 other insects, have appeared, and these are fraught with 

 deep thought and minute discrimination : in Britain at the 

 present time there exists no reference to which one may turn 

 for enlightenment upon this subject, which was partly and 

 incomprehensively treated of by Stephens in 1835, and super- 

 ficially commenced, though never completed, by Bridgman 

 and Fitch in 1880. 



To turn, however, from their many intricacies to the ease 

 with which quite a large collection of Ichneumons may be 

 compiled, we find them exhibiting an almost human love of 

 this world's sweets. They are often found upon the " sugar" 

 placed for the delectation of moths on tree-trunks at night, 

 and during the daytime umbelliferous and other flower- 

 heads often teem with yellow-, red-, blue-, and white-marked 

 specimens of these pretty insects. Some kinds prey upon 

 aquatic larvae, possess the power of running, like Gerris 

 and certain species of Stenus, upon the water, and may 

 often be swept from reeds and sedges. Some are attracted 

 by artificial light during the hours of darkness ; and others 

 pass the winter in the perfect state among moss, fallen 

 leaves, and at the roots of grass. Species which prey upon 

 caterpillars living deep in the solid wood of trees are pro- 

 vided with very long ovipositors with which to reach their 

 victims, and are said to bore with them through the hardest 

 wood ; species which attack fully-exposed larvae have a very 

 short ovipositor, hardly visible beyond their body. The old 

 theory, presupposing that each parasite was restricted to a 

 particular host, is now exploded by the breeding of many 

 different kinds from a single one ; and we may take it that 

 the only restrictions to be ascribed to parental instinct are 

 those of the adaptability of the host to sustain the Ichneumon 

 grub till it shall have attained maturity. 



