18 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



beaker so that the vial v^^ill not actually 

 touch the bottom ; heat the beaker until the 

 water boils; the caustic solution will not 

 boil. This water bath treatment guards 

 against overclearing of the specimen. After 

 the viscera are more or less extracted, trans- 

 fer the specimen through at least three 

 baths of distilled water, leaving it at least 

 1 hour in each, and then place it in a dish 

 of alcohol to which a few drops of 1 per 

 cent acetic acid solution have been added. 

 Remove the preparation to neutral alcohol. 

 It is now ready to study. 



For liquid preservation, the cleared geni- 

 tal capsule and the specimen to which it be- 

 longs can be placed together in a small shell 

 vial 74 by 4 mm. ; this vial can then be filled 

 and stopped with a cotton plug and inverted 

 in a ring-neck, 3-dram vial. Hard red rub- 

 ber stoppers are desirable for these vials; 

 to insert stopper, wet it with alcohol, place 

 a long pin alongside it and insert both to- 

 gether into the neck of the vial as far as 

 desired ; then hold stopper in place and pull 

 out pin. This technique allows air to escape 

 from the vial as the stopper is inserted and 

 prevents air pressure from being built up 

 inside the vial below the stopper. 



For pinned specimens the genital capsule, 

 if not too large, may be placed in a minute 

 shell vial with a small amount of glycerine 

 in the bottom. The vial can be corked and 

 mounted under the specimen by simply run- 

 ning the specimen's pin through the cork. 

 The genitalia can be removed from this con- 



tainer with a pin which has a minute hook 

 at the end. For further details, see article 

 about this procedure by DeLong & David- 

 son (1937). 



For study under a compound microscope, 

 these cleared genitalia may be placed in pure 

 glycerine. Very convenient for such study 

 is a slide with a ground-out place or well 

 in which the glycerine may be placed. Mi- 

 nute angles may be made from fine wire or 

 pins and these used in the glycerine to keep 

 the preparation in place while it is being 

 studied or drawn. The glycerine keeps the 

 preparation perfectly flexible and it also 

 has a fine refraction, even when a cover 

 slip is not used. Glycerine and alcohol are 

 readily miscible so that preparations may 

 be transferred from one to the other with- 

 out harm. 



For the family Hydroptilidae it is desir- 

 able to clear the entire specimen without 

 detaching the abdomen. The procedure is 

 the same as above except that in this case 

 it is necessary to tear a slit in the base of 

 the abdomen through which the dissolved 

 viscera may be expelled. This technique 

 destroys a clear view of the wing venation, 

 but this is seldom decipherable even in an 

 uncleared specimen and does not appear 

 essential now for either family or generic 

 diagnosis. On the other hand, characters 

 of the ocelli, legs, thoracic structure and 

 genitalia, which are all essential for identi- 

 fication, are not plainly visible without clear- 

 ing. 



CLASSIFICATION 



Adults of the order Trichoptera are dis- females of several genera), covered with 

 tinguished by the following combination of setae which may be hairlike or modified into 

 characters: head with long antennae; 

 mouthparts with vestigial mandibles, well- 

 developed maxillary and labial palpi, their 

 parent sclerites more or less fused to form 

 a flabby, proboscis-like structure; thorax 

 with tergites and pleurae normally divided; 

 two pairs of wings present (abortive in the 



Fig. 19. — Lepidoptera. A typ- 

 ical moth showing the scales on 

 wings and body and the sucking 

 tube, which is coiled up under 

 the head when not in use. Spe- 

 cies in which the tube is poorly 

 developed or entirely lacking al- 

 ways have the wings with a very 

 dense and uniform covering of 

 scales. 





^^ 





