588 FSTCHH, 
Having found these interesting glands 
on the larvae of Altacus cecropia, glands 
concerning which I can find no mention 
in entomological literature, my attention 
was drawn further to the subject of exter- 
nal glands of insects, many of which are 
protective or defensive in function. 
Glands similar to those of the larva 
of Attucus cecropia, in that they have no 
outlet until one is produced by external 
agency, are not rare in the larvae of 
bombycidae. The severe poisoning pro- 
duced by the hairs of certain larvae of 
bombycidae, of which the so-called pro- 
cessionary caterpillar of Europe is an 
example, and observed, according to 
Monfet,* by Dioscorides and other early 
writers, is caused by the secretion from 
minute gland at the base of each hair. 
The secretion of these glands fills the 
hollow central portion of the hair, and 
when the sharp, often barbed, hairs are 
broken in the flesh of attacking animals, 
the broken parts carry with them the 
poisonous secretion. This secretion is, 
perhaps, formic acid or a formate in solu- 
tion. Karsten,? in 1848, described the 
anatomy of the poison glands at the base 
of the hairs of an American species of 
Suturnia. Fine illustrations of this kind 
of gland are to be found in the stinging 
hairs of the larvae of Hyperchiria io and 
Hemileuca maia, both common insects 
in parts of the United States. Lintner? 
and Riley* have recorded their experi- 
ments on the stinging power of these 
two species of larvae, and the latter 
writer has given a list of the larvae of 
1For literature referred to throughout this paper see 
the end of the article. 
American species of lepidoptera which 
are known to sting. Lintner has experi- 
mented further upon the stinging power 
of the larvae of Lagoa crispata, and Miss 
Murtfeldt® upon that of the larva of 
Lagoa opercularis. That the sting of 
some of these larvae can do lasting in- 
jury is certain, for my mother, when 
twenty-seven years old, received so 
severe a sting in the middle finger of one 
hand in brushing away a larva from he? 
neck that the distal joint, healing only 
after several months, remains somewhat 
stiffened and slightly deformed, now thir- 
ty-seven years. For a time the stinging 
of these bombycid larvae was attributed 
to the action of the hairs in entering 
and wandering about in the flesh, and, 
even as late as 1881, long after the dis- 
covery of the glands at the base of the 
hairs, Goossens® advances the idea that 
the poison of the processionary caterpil- 
lar of Europe comes from other glands 
which I shall mention more in detail 
later. Keller,’ in 1883, discusses the 
mode of urtication in the processionary 
caterpillars (larvae of Giastropacha) and 
figures the glands at the bases of their 
hairs. 
Still another form of gland without 
any outlet until broken open, but a gland 
which can scarcely be classed with those 
previously mentioned, is that at the an- 
terior end of certain bombycid pupae, 
which breaks when the imago springs 
the chitinous pupal skin, and leaves its 
secretion, which has been termed bomby- 
cic acid, on the head of the moth, the 
latter using the secretion to moisten the 
threads of the cocoon so that they can 
