REVISION OF STREPSIPTERA PIERCE. 13 



Hence two very feasible methods may be suggested. Very fine 

 balsam mounts can be made by supporting the cover glass with 

 broken slivers of a glass slide. This prevents the specimen from 

 being crushed. Glass rings serve the same purpose, but are more 

 expensive. If not desired to make permanent mounts, the speci- 

 mens may be kept in alcohol and examined under a high-power 

 microscope as follows : Glue a glass ring on a slide with some substance 

 unassailable by alcohol, fill the cell with alcohol, and, after placing the 

 specimen in position, carefully slide a cover glass over it. This will 

 give opportunity to use quite a high power on the object and takes 

 but a minute or two to transfer from the bottle to the slide and back 

 again. Slides with permanent cells may be purchased. 



BIOLOGY. 



The life history of the Strepsiptera is of so much interest that it 

 appears well to introduce the more specialized treatise of the biology 

 by a brief summary of the most important elements in it. 



These insects are called in common parlance "stylops, " and stu- 

 dents, when speaking of a parasitized insect, usually say that it is 

 "stylopized." The "stylops" is known to most collectors only as a 

 disk-like or acarus-like plate protruding from between the abdominal 

 segments of various bees and wasps. Few, indeed, are they who have 

 seen the adult winged males, although most collectors have marveled 

 at the pictures of them. In fact, many a careful collector would 

 never even notice the foreign body in the abdomen of his specimen. 



If this disk-like plate is flat the parasite is an adult female, and 

 the part seen is the cephalothorax, a character not appearing in other 

 insects. The part unseen is merely the grub-like white abdomen 

 which often almost fills the body of the host. If instead of a disk 

 the part exserted is the tuberculate rounded end of a cylindrical 

 body the collector may know that he has a male pupa, from which 

 an adult active male will emerge if he keeps the host alive. 



With the grub-like female the discussion of the life history may 

 commence. Dissect it out, and you will usually notice that just 

 where it protrudes its cephalothorax there is some kind of firm con- 

 nection with the body of the host, which sometimes happens to be a 

 tube. These insects draw their nourishment from their host by os- 

 mosis, which is the most degraded manner of alimentation. The 

 body of the female is a great sack full of eggs, all of which develop at 

 the same time, and not in ovaries but loose in the body cavity. The 

 real female never sheds its last skin. It has lost all instinct, except 

 that which causes it to force its chitinized cephalothorax out through 

 the abdomen of its host. Yet in spite of this its nervous system is 

 as highly developed as the male's. 



