Holmgren, Emil. Studier öfverhudens och de körtelartade hudorganens morfologi hos skandinaviska macrolepidopterlarver. (K. Svenska Vetenskaps-Akademiens Handlingar, xxvii, No. 4, Stockholm, 4º 1895, pp. 82, 9 Pls.)
Lutz, K. G. Das Blut der Coccinelliden. (Zool. Anzeiger, 1895, pp. 244–255, 1 Fig.)
Gilson, Gustav. Studies in insect morphology. (Proc. Linn. Soc. London, March 5, 1896; Nature, p. 500.)
—— On segmentally disposed thoracic glands in the larvæ of the Trichoptera. (Journ. Linn. Soc., London, xxv. 1897.)
Cholodkowsky, N. Entomotomische Miscellen, v, Ueber die Spritzapparate der Cimbiciden Larven, pp. 135–143, 2 Taf. Ibid., vi. Ueber das Bluten der Cimbiciden Larven, pp. 352–357, 1 Fig. (Horæ Soc. Ent. Rossicæ, xxx, 1897.)
Also the writings of Darwin, Wallace, Poulton, Weir, Beddard, Butler, Busgen, (pp. 365–367), Girard, Kolbe, Locy.
THE ALLURING OR SCENT-GLANDS
It is difficult to draw the line between repelling and alluring glands. Attention was first definitely called to the alluring odors of Lepidoptera by Fritz Müller, who showed that the males of certain butterflies are rendered attractive to the other sex by secreting odorous oils of the ether series. He pointed out that the seat of the odor is the androconia (see p. 199), while either repellent or pleasant odors are exhaled from abdominal glands.
Those of Pieris napi yield a scent like that of citrons, Didonis biblis gives off three different odors from different parts of the body, besides having a distinctly odorous spot on the hind wings. Both sexes have a sac between the fourth and fifth abdominal segments which exhales a very unpleasant (protective) odor, while the males have on the succeeding segment a pair of glands from which proceeds an agreeable odor like that of the heliotrope. Callidryas argante throws off a musky odor. In Prepona laertes the odor is like that of a bat, in Dircenna xantho it is vanilla-like, the androconia being situated on the front edge of the hind wings. In Papilio grayi the odor is said to be as agreeable and intense as in flowers. Certain sphingids are known to exhale a distinct odor, which Müller has traced to a tuft of hair-like scales at the base of the abdomen, and which fits into a groove in the first segment, so as to be ordinarily invisible.
