No. 628] HABITAT RESPONSES OF WATER-STRIDER 401 



there was little to indicate its location except a small 

 area of rapidly drying mud. 



3. Hibernation mid Estivation. — A number of writers 

 -among others Uhler (1888, pp. 268, 275), MeCook (1907, 

 p. 265), and Kellogg (1908, p. 198)- on walor-striders 

 have stated that during hihernntloii these ucn-ids hur- 

 row^ed into the mud, under the hanks of streams, at the 

 bottom of water under stones and roots of trees, and at the 

 bottom of the pool under roots or stones; and as some 

 investigators. Tower (1906, p. 245), for example, con- 

 sider hibernation and fPstivation to be "fundamentally 

 one and the same process." I was intorestod to observe 

 whether the gerrids would l)nn-o\v into tlie imid. or into 

 some moist, sheltered s])()i niidei' the banks of tlie brook, 

 and remain there in a ([nioscent condition, a state of 

 aestivation, until the rains came. However, there were no 

 definite responses of such a character. I doubt whether 

 water-striders do restivate in the true sense of that term 

 during periods of drought, althongli more evidence is 

 necessary before a definite statement can l)e niadi^ 



As will be noticed latei-. tlu^ uei ri«l< (h) ic-pdnd to con- 

 tact stimuli. Generally sneh a -tiinnlii- re-iilicd in in- 

 hibiting locomotor activity and the insect- remained 

 motionless with their bodie> eln-ely a]»|ilied i«. -imie H)hM 

 object in the bed of the hr.u.k. 'IMii- miulit pi nxc t(. he a 

 piece of drv nmd. a stiek of driftwei.h a -tone, or a chim]) 

 of deadleaV.'s. Asa resuh ore<.ntaet st inudi, sometimes 

 they w<.idd eraxvl under sueh ohjret- as have h,-en enu- 

 merated and nMP.ain there for a eon.-iderahlo leu-tli of 

 time. 1 have re.M.rd.Ml oh.civat i-.n- wliieh prove that tli.n- 

 Stayed in -ueh Htuation- from a feu- -eeend- to thirtv 

 minutes. The uvrrid- mi-Id remain in ])lae,-s of tliis 



few o,-,.aHen^. that thev wre Mill tln^re when 1 di-.-on- 

 tinued niv oli^'rvat ion- t'ni- the .h'lv. Ih.wevm-. I wa- tmt 

 a})le to iin<l them in the -ame situation \W next day. even 

 after nio-t earefully markinu' tlie phace. On M'veral other 

 occasion-. I have made .innlar oh-m-vat ion>. hut never 



