2 Fleas of Eastern United States 



Hence, it is customary to use 10% potassium hydroxide in 

 water to dissolve the unsclerotized structures. It is best not to 

 boil the KOH, but to use it cold and allow action to go on for 

 a day or two. Care should be taken not to allow the caustic to 

 act too long, for it will distort, or even dissolve away entirely, 

 important taxonomic structures. After its removal from KOH. 

 the material is washed in water and dehydrated by use of sev- 

 eral degrees of alcohol. If the material is to be cleared in xylol 

 or oil of cloves, it is best to run it through two changes of ab- 

 solute alcohol. The absolute alcohol may be eliminated, how- 

 ever, if beechwood creosote is used as a clearing agent. 



The writer makes use of the following technique which re- 

 duces the entire procedure to six steps: 



1. Drop living flea (or one which has been killed in 

 alcohol) in KOH 10% in water. Allow to remain for a day 

 or two. 



2. Transfer to water to which a few drops of HC1 have 

 been added. Allow to remain for one-half hour. 



3. Dehydrate by running through 50 % alcohol and 



4. 95% alcohol for one-half hour each. 



5. Clear in beechwood creosote for one hour. 



6. Mount in Canada balsam. 



It is essential to label adequately. Two labels are generally 

 used for each glass slide. One, placed to the left, bears the name 

 of the flea and by whom it was determined; the other, placed 

 to the right, bears the name of the host, the locality, the date, 

 and the collector's name. 



MORPHOLOGY AND TERMINOLOGY 



The body of the flea, like that of all insects, is divided into 

 head, thorax, and abdomen, and each of these regions is of im- 

 portance in taxonomy. In the suborder Fracticipita the head is 

 subdivided by a dorsal sulcus extending from the place of in- 

 sertion of the antenna on one side across the dorsum to the 

 place of insertion of the antenna on the other side. The fleas of 

 the suborder Integricipita, however, have no such sulcus, al- 

 though there may be a highly sclerotized thickening extending 

 from the top of the antennal groove to the dorsum of the head. 

 Antennae, one on each side, are situated in antennal grooves 

 which set off on the head a preantennal region and a post- 

 antennal region, each of which may be armed with bristles the 

 arrangement of which is of great aid in classification. The upper 



