410 ENTOMOLOGICAL SOCIETY 



sects undergoing complete metamorphosis, since the female 

 imago is dependent on the life of her host. Nevertheless, in no in 

 stance can Coleopterous parasitism come within my first category 

 unless Phatypsyllus prove to be sedentary in all stages upon its 

 host. 



DIPTERA. There are no truly parasitic species among the 

 Lepidoptera, the Homoptera, or the Thysanoptera, and while in 

 the Heteroptera we have certain species, like the common bed 

 bug, which have acquired a pseudo-parasitic, life upon warm 

 blooded animals, and which point out to us the manner in which 

 the true lice have probably originated, yet the parasitism of 

 Acanthia is a very low form not embraced in either of mv 

 categories. When we come to the Diptera, however, we find 

 a very instructive instance of parasitism. The Tachinidas are 

 probably the most completely parasitic insects of the order, 

 and from the great extent of the family (including a number 

 of sub-families) the many genera, and the numerical abund 

 ance of the species in individuals, they rank next to the 

 parasitic Hymenoptera in destruction to insects of other classes. 

 The female lays her rather tough, ovoid, white eggs upon the 

 skin of caterpillars, locusts, and other insects. The eggs hatch 

 into white, footless maggots, which bore into the host insect and 

 live concealed until reaching full growth, when they issue and 

 transform, generally in the ground near bv, into ovoid, brownish 

 puparia, from which eventually come forth the adult flies. Some 

 little time elapses after the laying of the egg before this hatches, 

 and in the interval many insects, especially hairy caterpillars, 

 may save themselves in molting, by shedding the eggs of the para 

 site with the cast skin. This, however, occurs onlv when the 

 Tachinid egg is laid about the time of molting, and the vast 

 majority of the insects attacked are eventually killed by the para 

 sitic larvas. The Tachinid fly seems to waste many eggs, and a 

 caterpillar which will support not more than a dozen of the para 

 sitic larvae will be found sometimes bearing 50 or more eggs. 

 As a rule, these eggs are placed in such positions that they can 

 not be reached and removed by the jaws of the host insect. 



Miltogramma is an interesting genus of Tachinids which preys 

 upon larvae stored by bees or wasps. It greatly resembles the 

 Sheep Bot-fly ( CEstrus ovis), and also mimics the color of the sandy 



