1915} Life History Thelia Bimaculata 147 
and they would doubtless have escaped unnoticed had it not 
been for the movements of the large ants running briskly about 
them. Birds apparently avoid the insect. No case of their 
being eaten by birds has been observed in the field, and several 
handfuls thrown to birds in captivity were refused, although one 
or two individuals were picked up, only to be dropped again. 
Evidently the strong pronotal horn and the sharp posterior 
process (the latter being sharp and hard enough to pierce the 
skin if the adult insect is suddenly seized) and the hard prothorax 
are sufficient protection from bird enemies. The bodies of 
these insects are occasionally infested by a small red mite, and 
not infrequently a membracid is found in a spider’s web. 
ATTENDANCE By ANTS. 
The attendance by ants on various species of Membracidez 
has often been recorded. Interesting notes have been pub- 
lished on this subject by Mrs. Rice!, Miss Branch?, Belt*, Green!, 
and Lamborn’, and attention called to the fact by other authors. 
In the case of Thelia bimaculata this is a most noticeable and 
interesting feature of their life-history. The species of ants 
which have been found attending both nymphs and adults have 
been very kindly determined by Professor W. M. Wheeler as 
follows: Formica obscuriventris Mayr, Formica exsectoides Forel, 
Camponotus pennsylvanicus DeGeer, Crematogaster lineolata Say 
and Prenolepis imparis Say. 
ECONOMIC IMPORTANCE. 
Thelia bimaculata can hardly be considered as an insect of 
economic importance in so far as any damage to the tree caused 
by its presence is concerned. The amount of sap consumed is 
apparently very small and the method of egg-laying has prac- 
tically no injurious effect on the host. The fact that the egg- 
slits are very narrow and placed longitudinally, makes it possible 
for the bark to quickly heal over the wound and the scars have 
1Rice, Mrs. M. E. Insect Life. 1898. Vol. V: No. 4. 243-245 p. 
Branch, Hazel E. Morphology and Biology of the Membracide of Kansas. 
Kans. Univ. Bull. 1913. ae VIII: No. 3. p. 84. 
3Belt, T. Honey exuding Membracide attended by ants. Naturalist in Nic- 
aragua. 1874. 
4Green, E. E. Note on the attractive properties of certain larval Hemiptera. 
Ent. Month. Mag. Aug. 1900. Vol. XX XVII: p. 185. 
5Lamborn, W. A. Ants and Membracide. Trans. Lond. Ent. Soc. 1918. 494- 
498. p. 
