$ 347. THE INSECTA. 445 
There is another category of secretory organs which, with many females, 
open at the base of the ovipositor, but as they are intimately connected 
with the act of oviposition, they will be most properly described with the 
genital organs.“ 
A very large majority of the holometabolic Insecta have, in their larvae- 
state, silk-organs, the secretion of which they use, some, to weave a cocoon 
when about to pass into the pupa-state, or to close a hellow refuge they 
have sought; others to fasten together foreign bodies for the fabrication of 
their retreat. These organs are, therefore, most developed at the period 
when these insects approach their pupa-state; but with the larvac of the 
Psychidae, Tortricidae, and Lasiocampadae, they are already active during 
the first epochs of life. The silk-secreting portion of this glandular apparatus 
consists of two long, somewhat flexuous, thick-walled caeca, situated on the 
sides of the body, and continuous, in frout, into two small excretory ducts, 
whose common orifice is on the under lip, and usually at the extremity of 
a short tubular protuberance.“® | With the larvae of Myrmeleon, the silk- 
apparatus is very remarkable, for the rectum itself is changed into a large 
sac and secretes this substance, which escapes through an articulated spin- 
neret projecting from the opening of the anus.“ 
With the Apidae, there is a very remarkable Wax-secreting apparatus. 
This wax is elaborated by the Workers under the form of thin discs, which 
are formed between the imbricated posterior legs, without there having 
been discovered, as yet, in this region, the orifices of any special glands. 
It must therefore be supposed that it is produced by an exudation from the 
thin membranes which connect the different parts of the legs.“ Moreover, 
many other Insecta have secretory products which transude through the 
skin without the existence of any special glandular apparatus, and which 
are hardened by the air like wax. These products are usually whitish, 
pulverulent, filamentous, or floceulent substances, which catch upon the 
surfaces of bodies.” 
a 
13 See § 350. Institut. 1848, also in Froriep’s neue Not. 
14 See Roesel, Insektenbelust. III. Class. I. Pap- 
jlionum nocturnorum. Taf. IX. (Bombyx) ; Lyonet, 
Traité, &c., p. 498, Pl. XIV. XV. (Cossus) ; 
yuckow, Anat. u. physiol. Untersuch. p..29, Taf. 
VII. fig. 31 (Gastropacia); Pictet, Recherch. 
pour servir a Vhist. d. Phryganides, Pl. III. fig. 1 
(Phryganea). The decrease of these organs dur- 
ing the pupa-state has been very carefully detailed 
by Herold, Entwickelu h.d. Sch 1., Taf. 
I. and by Suckow, loc. cit. Taf. IL. (Pontia, 
Gastropacha). 
15 See Réeaumur, Mém. &c. VI. Pl. XXXII. fig. 
1,85 Ramdohr, Abhandl. &c. Taf. XVII. fig. 1. 
16 For the intimate structure of the wax-secret- 
ing portions of the skin with the workers of bees, 
see Treviranus, Zeitsch. f. Physiol. III. p. 62, 
225 ; and Brandt and Ratzeburg, II. p. 179, Taf. 
XXYV. fig. 18. The production of wax with bees has 
lately been the subject of much research among 
French naturalists. Milne Edwards has ad- 
vocated the opinion before rejected by him, that this 
substance is secreted by special glands. But L. 
Dufour, after carefully-made researches, failed to 
discover them. See the various memoirs on this 
question in the Compt. Rend. XVII. and in the 
* [ § 347, note 17.] See upon the subject of these 
secretions Dujardin (Mém. sur étude micros- 
38 
XXVIIL. XXIX. 
It is, moreover, easy to be convinced of the ab- 
sence of these glands with the bee-workers ; but 
if certain Andrenidae are examined, there will be 
found, on each side of their posterior tibiae, a small 
pyriform follicle with an excretory duct, and which 
secretes an oily substance. 
17 These cutaneous secretions are observed with 
various Coccidae and Aphididae, whose entire bodies 
they cover with a powdery or woolly substance. 
With the females of Dorthesia, not only the entire 
body is covered with a substance which forms a 
solid white crust, but alse the eggs after their depu- 
sition are invested with a similar envelope ant 
thereby glued to the abdomen of the mother. With 
many male Coccidae, this secretion forms, at the 
posterior extremity of the abdomen, a bundle of 
very diverging, long, white and perishable haire 
With some Cicadidae (Lustra and F lata), we 
thorax and abdomen are covered, in places, by a 
kind of mould of a similar origin. The larvae of 
many Tenthredinidae (for example, Tenthredo 
ovata), as well as those of certain Cocvinellidae 
(Scymnus), exude a liquid which, upon drying, 
forms white flocci.* 
copique de la cire, in the Ann. d. Sc. Nat. XIL 
1849, p. 250); his observations were made upon 
