68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 68 



COLEOPTERA 



The simplest type of a scent-producing organ in beetles is com- 

 posed of unicellular glands distributed over the entire body surface. 

 In some beetles these unicellular glands are grouped and thus form 

 glands varying considerably in complexity. In Malachius two pairs 

 of caruncles serve as the scent-producing organs ; unicellular glands 

 lie in the walls of these structures. In Dytiscus, Gyrinus, and 

 Acilius two different kinds of liquids issue from unicellular glands 

 located in the articular membranes between the thoracic segments. 

 The liquid emitted at the femoro-tibial articulation during the reflex 

 bleeding of certain beetles seems to be secreted by two types of 

 unicellular glands at this location. 



The highest type of a scent-producing organ in all insects is the 

 anal glands of beetles. These glands have been found in the follow- 

 ing families and subfamilies : Cicindelidcc, Carahina:, HarpalincE, 

 Feroniince, Brachinincu, Dytiscida ,Gyrinidcc , StaphylinidcB, Silphidce, 

 and Paussidcc. They are usually paired, vary considerably in com- 

 plexity and are probably present in both sexes. The most complex 

 form consists of an efferent canal, a spherical capsule, a reservoir, 

 collecting tubes and unicellular glands, each of which contains a 

 radial vesicle from which runs a secreting tubule to the collecting 

 tube. 



LEPIDOPTERA 



Butterflies. — The scent scales on the wings constitute the almost 

 universal type of scent-producing organs in male butterflies. A 

 unicellular gland lies at the base of each scent scale. A pair of 

 invaginated sacs located at the ventro-posterior end of the abdomen, 

 has been found, however, in the males of Danais septentrionales and 

 Euplcea asela. These sacs are partially lined with scent hairs and at 

 the base of each hair lies a unicellular gland. In the female of 

 Euplcea asela, the same organ is present, but in addition there is a 

 circle of scalelike, scent hairs around the anus. In the female of 

 Gonopteryx rhamni, the scent-producing organ is a single invaginated 

 sac similarly located. In the females of the maracuja butterflies, a 

 pair of styled knobs located at the posterior end of the abdomen 

 serves as a scent-producing organ. 



Moths. — The most common type of scent-producing organ in male 

 moths is a tuft of scent hairs on the tibiae of the third pair of legs. 

 Occasionally, however, tufts of hairs are found on the tibise of the 

 first and second pairs of legs. A unicellular gland lies at the base of 



