Wasps 



The parasitic family Bethylidae, which Ashmead has trans- 

 ferred from the Proctotrypoidea to the Vespoidea, is a group of 

 small insects. The family Trigonalidae, now placed here, but 

 formerly placed near the Ichneumon flies, is also parasitic ; they 

 live parasitically in the nests of Polistes and Vespa, agreeing in 

 habits with the Sapygidae. 



The Bethylids are all, so far as we at present know, parasitic 

 upon caterpillars and upon beetle larvae, usually upon very small 

 larvae. Haliday, the Irish entomologist, many years ago, wrote 

 an interesting account of the parasitism of some little Tineid larvae 

 by a species of Bethylus; but in this case the parasite was observed 

 to drag its little caterpillar victim into a hole in a reed. Possibly 

 this fact had much to do with the original suggestion, which came 

 from Haliday, that the Bethylidae should be placed nearer the 

 wasps than with the true parasitic Hymenoptera. In the typical 

 life history which follows, however, we will see that members of 

 this family are true parasites. 



Typical Life History 



As has just been shown, the habits of the insects of this great 

 group are so diverse that no one life history could be considered 

 as in any way typical of the whole group. As a matter of fact, 

 the proper and complete study of no one American species has as 

 yet been made. Many of these insects are everywhere to be 

 found, and life histories of surpassing interest and of much novelty 

 await the first careful person who will care to devote the necessary 

 time to this study. Of course a great deal is known about the 

 general economy of our social wasps and interesting studies have 

 been made by the Peckhams and others on some of the solitary 

 wasps which belong to this super-family, as well as to the Sphe- 

 coidea; but it is the parasitic forms, especially of the Scoliidae, 

 Myzinidae and Tiphiidae, which offer great opportunities. So do 

 especially the Mutillidae and the Chrysididae. Of one of the Bethy- 

 lidae, I am fortunately able to give some account, since it has been 

 studied with care in my laboratory by Mr. August Busck, from 

 whose unpublished notes the following interesting story is drawn. 



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