OF WASHINGTON. 405 



midges (Cecidomyiidae). Yet in many other genera, such as 

 Pteromalus, Eupelmus, Encyrtus, Microdus, etc., species are 

 parasitic upon insects of very different families, or even orders. 

 I have reared species of Eupelmus, for instance, from Lepidop- 

 terous, Orthopterous, and Hemipterous eggs ; from Cynipid galls, 

 from free Cecidorayiid larvae, from Cecidomyiid galls, from Lep- 

 idopterous larvae, from Coleopterous larvae, from Hymenopterous 

 cocoons, and from the egg-bags of spiders. 



Many of these parasites prey upon each other, thus bringing 

 about the habit which is known as hyper-parasitism, and tertiary 

 or even quaternary parasitism must often occur, though the proof 

 is difficult to obtain. We know, however, that in the case of 

 the common Bag Worm {Thyridopteryx ephemerceformis) 

 there is at least tertiary parasitism. 



Our fellow-members Mr. Howard and Mr. Ashmead have 

 become authorities respectively in the Chalcididae and Procto- 

 trypidae, and their numerous communications to the Society have 

 presented many facts well known to you in corroboration of these 

 generalizations ; while it would extend this address altogether too 

 far to go further into detail as to the habits of the different genera. 



COLEOPTERA. Next in ordinal importance in the character, if 

 not the number, of parasitic forms which they furnish are the 

 Coleoptera, to which belongs that very abnormal family, the 

 Stylopidae, which was, by Westwood, made the type of a distinct 

 sub-order (Strepsiptera). Morphologically these insects are 

 most interesting, and, while belonging to my second category, 

 approach more nearly to the true parasites of the first category 

 than any of the Hymenoptera ; for, except for the very ephem 

 eral winged and independent life of the male, these insects are 

 just as necessarily confined to and dependent upon their host in 

 all other stages of development as are the true lice and bird-lice. 

 The males are minute winged objects, lacking elytra, and have 

 more or less rudimentary mouth-parts, while the females are 

 wingless, worm-like, with flattened triangular tip, and live just 

 under the skin in the abdomen of many species of wasps, bees, 

 and even ants and a few Homopterous insects. A new form has 

 recently been discovered in Africa which is parasitic upon the 

 mole-cricket. The female Stylopid is viviparous, giving birth to 

 hundreds of very small young which are of primitive form, with 



