296 STRANGE DWELLINGS 



and is evidently the produce of some lepidopterous insect, pro- 

 bably a moth allied to the silkworm. Upon the larva which 

 construoied the cocoon an ichneumon has laid her eggs, and 

 the consequence has been that the caterpillar has been unable 

 to change into the pupal condition, but has succumbed to the 

 parasites which infested it. These insects are not of minute 

 dimensions, like the Microgaster, but are tolerably large, and 

 in consequence can be but few in number. The cells are very 

 irregular in shape, and are not rounded like those of many 

 Ichneumonidae, but have angular edges. 



Within the same case there are several cgcoons in which a 

 similar calamity has befallen the caterpillars which made them. 

 There is, for example, a cocoon of the Oak-Egger Moth {Lasio- 

 campa quercus)^ the interior of which resembles that of the insect 

 which has just been described, except that the cells of the parasite 

 are more numerous. This species of caterpillar is peculiarly 

 subject to the attacks of the ichneumon flies, as is well known 

 to all practical entomologists, who lose niany of their carefully 

 bred specimens by means of these insects. 



There is also one of the winter cocoons of the Goat Moth 

 caterpillar, the inmate of which has been pierced by the ichneu- 

 mon fly, and killed by its young. As the species of ichneumon 

 is a large one, only a single individual was produced, and as may 

 be seen from the cell of the parasite which is placed by the side 

 of its victim, the habitation of the ichneumon is so large that it 

 must have occupied nearly the entire cocoon of the dead cater- 

 pillar. 



Those splendid insects which are popularly called Ruby- 

 tailed Flies, or Firetails, and scientifically are termed 

 Chrysididce, are also to be numbered among the parasitic in- 

 sects. 



They make no nests for themselves, but intrude upon those 

 of various mason and mining bees, and several other insects. 

 The Firetail does not, however, lays its eggs in the body of the 

 iarva, but makes its way into the nest while the rightful owner 



