§347. 



THE INSECT.' 



443 



alone, their number is smaller,"^' and with those of the Lepidoptera. the 

 extremities of the six tubes of this kind are insinuated between the tunics of 

 the colon; while, with the imagines thej are free.'^"' With the Bupres- 

 tidae, the larvae have six, but the imagines ooly four, of these vessels.'^^' 



II. Organs of Peculiar Secretions. 



§ 347. 



A great number of the Insecta, in both their larval and their perfect state, 

 have glandular oi-gans which secrete very varied products remarkable for 

 their specific properties. 



Many species have a secretory apparatus analogous to the cutaneous 

 glands of the Vertebrata, which have received the name of Glandidae odor- 

 iferae. These consist of round follicles situated under the skin, whose 

 very short excretory ducts open between the segments of the body, or be- 

 tween the articulations of its extremities. Their product emits a powerful 

 odor, and, with some species, is evacuated in the form of droplets,"* or, 

 with others, covers the whole surface of the body, being perceived only by 

 its odor.'* The disagreeable odor emitted by the Bugs is due to a fluid 

 secreted by a single, yellow, or red pyriform gland, situated in the centre 

 of the metathorax, and opening between the posterior legs.<^' With other 

 Insecta, there are analogous secretory organs, concealed in the posterior 

 extremity of the abdomen, which copiously emit a fetid, troubled liquid, 

 through an orifice situated by the side of the anus. These Anal Glands are 

 usually double, and consist of simple follicles whose secretory product 

 accumulates in round, or oblong contractile reservoirs.'^' With many 



(larva of various Lamellicornes); and Burmeister, 

 Trans, of the Entom. Soc. I. PI. XXIV. fig. 10 (larva 

 of a Calosoma), and his Abhandl. z. Naturges- 

 chichte d. Calandra, loc. cit. fig. 3. 



ly The larvae of the Apidae and Vespidae have 

 only four uriniferous vessels ; see Suiammerdamm, 

 Bib. der Nat. Taf. XXIV. fig. 6 (larva of a bee) ; 

 Suckow, in Heu.iin^er's Zeitsch. III. Taf. VI. lig. 

 180, and Ramdokr,\<x. cit. Taf. XII. (larva of a 

 Vespa) ; finally, Rathki, in Miiller\^ Arch. 1844, 

 p. 36, Taf II. (larva of a Gryllotalpa). 



20 See Lijonet, Traite, &c., PI. XIII., and 

 SuckoWi Anat. u. physiol. Untersuch. Taf. II. 



21 See L. Diifour, Ann. d. Sc. Nat. XIV. 1840, 

 p. 114. Loew (Kntom. Zeit. 1841, p. 3t, fig. 3) did 

 not, probably, observe these canals in the larva of 

 Buprestis ■mariana ; for, otherwise, he would not 

 have regarded as such the two caecal appendages 

 at the upper e.\tremity of the stomach, and which 

 the Buprostidae have also in their imago-state (see 

 §338). 



1 With Euprepia, and Zygaena, a fluid of this 

 kind, yellowishly transparent, e.xudes under the 

 collar ; and with many Meloidae, Chrysomelidae, 

 and Coccinellidae, it escapes from the knee-joints. 

 The larvae of these last Coleoptera, as well as those 



of many Tenthredinidae, emit droplets of fluid from 

 the surface of their skin from the least touch. Very 

 often the odor of this fluid reminds one of fresh 

 poppy-juice. The fluid emitted from the cephalo- 

 Ijrothoracic articulation, with Colyinbetes and 

 Dt/tiscus, has a very nauseating order. I am un- 

 able to decide whether or not the transparent liquid 

 which escapes with various Aphididae through two 

 tubes on their abdomen, belongs to this same cate- 

 gory of secretions. 



2 Certain Phryganidae, Hemerobidae, Crabron- 

 idae, Scoliadae, Ichneumonidae, &c., emit specific 

 odors without the secretion of their Glandulae 

 odoriferae being visible. 



■■! See L. bufour, Recherch. loc. cit. p. 260, PI. 

 XVII. fig. 194. Moreover, the opinion tliat all the 

 Bugs emit a bad odor is incorrect ; for with many, 

 as for e.xample Syromastes, the Glandulae odori- 

 ferae exhales a very agreeable odor resembling that 

 of a fine bergamot pear.* 



•J These anal glands, which Burmeister (Ilandb. 

 I. p. 157), Grant (Outlines, &c., 1 >c. cit. p. 584) 

 and other anatomists have mistaken for urinary 

 organs, consist, with the Dytiscidae and Gyrinidae, 

 of two simple, long and flexuous caeca, whose re- 

 servoirs, having two short excretory ducts situated 



* [ § 347, note 3.] With Belostoma, the odor- abdomen. They open externally between the 



iferous glands consist of two pretty long caecal coxae of the posterior legs. See Leidy, loc. cit. p. 



tubes situated in the metathorax, beneath the other 64. — Ed. 

 viscera, and extending into the anterior part of the 



