132 NEBRASICA STATE HORTICULTURAL SOCIETY 



While this concludes the list of two-winged parasites, there are still 

 three groups of four-winged or Hymenoptorous parasites with which 

 the larvae of our insects have to deal. These are by far the more numer- 

 ous, and of much greater economic importance. They are easily dis- 

 tinguished from the flies by the presence of two pair of wings intead of 

 only one pair. The females are provided, as are the egg parasites, with 

 a long sting-like ovipositor which is used to penetrate the skin of the 

 caterpillar and deposit the egg beneath. The story of the development 

 of these parasites is so similar to that described previously that it need 

 not be repeated. It is apparent that this method is much more effective 

 than where the eggs are simply placed on the outside of the caterpillar 

 and exposed to various accidents before hatching. 



The Ichneumons, family Icbneumonidae, are the largest of the para- 

 sitic insects. The body is long, somewhat club-shaped, and these insects 

 might easily be taken as a kind of wasp by the casual observer were 

 it not for the long ovipositors of the females. One of our common and 

 largest Ichneumons is Tlialessn luuator. The body of this insect is about 

 two and one-half inches in length while the ovipositor of the female is 

 often seven inches long. This insect is parasitic upon the larvae of the 

 Pigeon Horn-tail which bores in the trunks of trees. The female Thales- 

 sa runs up and down the trunk of an infested tree, nervously tapping on 

 the bark till she finds a spot which she judges to be directly above a 

 burrow. The ovipositor is then made to form a loop and by a rhythmic 

 motion of the body made to penetrate the solid body of the tree till the 

 burrow is reached which sometimes is at a depth of three or four inches. 

 The egg is deposited and, when hatched, the young larva crowls along 

 the burrow until it comes in contact with the larva of the Pigeon Horn- 

 tail. Upon this the parasite feeds until it pupates. After having passed 

 through the resting stage, the adult insect emerges and gnaws its way 

 to the outside. 



The Long-tailed Ophion ( Ophion macruruni ] 

 an ichneumon. [After Riley.] 



