46 
Poisonous Arthropods 
these long hairs are numer¬ 
ous short spines connected 
with underlying hvpoder- 
mal poison glands. These 
hairs are capable of pro¬ 
ducing a marked nettling 
effect when they come in 
contact with the skin. 
This species is found in 
our Atlantic and Southern 
States. Satisfactory 
studies of its poisonous 
hairs and their glands have 
not yet been made. 
Sihine stimulea ( Em - 
pretia stimulea), or the 
saddle-back caterpillar 
(fig. 32), is another which possesses nettling hairs. This species 
belongs to the group of Eucleidae, or slug caterpillars. It can be 
readily recognized 
by its flattened 
form, lateral, brist¬ 
ling spines and by 
the large green 
patch on the back 
resembling a 
saddle-cloth, while 
the saddle is repre¬ 
sented by an oval, 
purplish-brown 
spot. The small 
spines are veno¬ 
mous and affect 
some persons very 
painfully. The 
larva feeds on the 
leaves of a large 
variety of forest 
trees and also on 
cherry, plum, and 
; ; V’. ■ :v. ___ s _ 5 __ 
32 The poisonous saddle back caterpillar. Empretia 
(Sibine) stimulea. Photograph by M. V. S. 
33a. Io moth larvae on willow. Photograph by M.V. S. 
