ON THE MECHANISM OF SUCTION IN LYGUS. PABULINUS. 685 
40, The Mechanism of Suction in the Potato Capsid Bug, 
Lygus pabulinus Linn. By P.R. Awart, B.A. (Cantab.), 
D.LC.(Lond.), Sir John Wolfe-Barry Research Scholar, 
Imperial College of Science, London *. 
[ Received January 31, 1914: Read March 17, 1914} 
(Text-figures 1-29.) 
INDEX. Page 
Introduction ..... BA ro ACS DNE ERE HUST IO EUnet RBS Geos ape ETE oF =D 
Material and Method .. PREP Ra Meatainngein en ptt ee eae) ORG. 
Hiomolerencothenviont erat Bopean esa cua cunbondtos68 doc aastas Doon oleH7/ 
Moxpholosyotstheviea dm rieece nesters cetseeenchcckc emcees ore cern Oe 
Tentorium ..... sel Bua edauels cutaiscon sate Aveueaeas son Mer Meaty ia AO 
Muscles of the Head RA ate dean can enero e cae ita) APD 
LEVEN a1ixg 8 For Hse a Ghanseidoeusacoa Da adelaaeetie ee On terlace Cac Roe a see pene eee aA LS) 
Gustatory Cues Sot nice cada care Dap caso BA caamec Doaaeouee EE MCE ERY OT 
PUMIp-ap Parabus ceawes see eee ese tee hs censotem ee encca teens teres CO 
Mechanism pacncnion Bn Renee Suen ee nantaNy eR Re a TA eae aR ees LO 
B31) StOyeRIEY OD) Fae ena neaasuees anu coc aBeNs ode Gee Hes ectdunas ScbaC ee noeseRe omen 732 
INTRODUCTION. 
The investigation of the mechanism of suction in Lygus 
pabulinus arose out of an inquiry by Professor Lefroy, of the 
Imperial College of Science, and Mr. Horne into the production 
by insects, on the foliage of the potato, of symptoms resembling 
those produced by fungi and by bacteria. They had produced 
definite symptoms by the infection of potato foliage with a Capsid 
(Lygus), a Jassid (Hupteryx), and other sucking insects; the 
symptoms were markedly characteristic of the differ ent species ; 
and the investigation of the actual mechanism of suction thus 
became necessary. I took up this inquiry at the suggestion of 
Professor Lefroy, who was in India at the time. 
The insect is common on the potato and other plants during 
the summer. More than one species of Lygus is concerned with 
the damage to the plants. The species used in this investigation 
has been identified by Mr. W. L. Distant at the Natural History 
Museum as Lygus pabulinus Linn. 
The scope of this paper is limited. It does not pretend to 
give full anatomical or morphological descriptions, but it describes 
the different structures of the head, both morphologically and 
anatomically, as far as they appear to be important in the 
mechanism of suction. 
I very gratefully acknowledge my indebtedness to Prof. Lefroy 
for his help and encouragement during the whole of my work, to 
Mr. Clifford Dobell for his valuable criticism and suggestions, and 
to Mr. H. G. Newth for his assistance in preparing the paper for 
press, 
* Communicated by Prof. H. Maxwett Lerroy, M.A., F.Z.S. 
47* 
