Biology of the Membra ctdae of the Cayuga Lake Basin 393 



Membracids are generally the most active during the warmest parts of 

 the day. Feeding, mating, oviposition, and flight have all been observed 

 oftenest during the hours from eleven o'clock in the morning until four 

 in the aftei'noon, and more activity is shown on extremely warm days 

 than on cool ones. This may be due to the fact that the bird enemies 

 of the insects are less numerous during the heat of the day, but such an 

 explanation can be advanced only as a theory. In the case of certain 

 species attended by ants it has been thought that the activity of the 

 membracids during the hours mentioned might be due to the activity 

 of the ants at that time. This, however, may be the converse of the 

 true reason, smce it may be that the ants are influenced by the mem- 

 bracids, and in either case there is no apparent reason why either insect 

 should show increased activity at definite periods. 



When at rest the msect generally chooses the underside of the flrst- 

 or second-year growth of trees or the upright stem of herbaceous plants. 

 The legs are spread rather widely apart, allowing the a]:)domen to almost 

 touch the host but keeping the hind legs in a suitable position for springing. 

 This position may be held for long periods of time, often for hours together, 

 tho actual records are not available owing to the fact that the patience 

 of the writer in timing the resting period of an indivitlual has never ccjualed 

 the pleasure of the insect. Some species have the habit of moving spirally 

 around the twig, the movement being very slow but sufficient to accomplish 

 a complete circuit of the twig in an afternoon. It has ])een thought that 

 this is done in an attempt to keep in the sunlight as the sun moves across 

 the sky, but this again is merely a conjecture. 



If approached, the insect usually moves around to the opposite side of 

 the twig or stem and makes no attempt to fly except as a last resort in 

 escaping. A slowly approaching object is not readily noticed, and the 

 insect may be touched with the finger before it moves if care is taken to 

 make the movement of the hand very slow and deliberate; a sharp, quick 

 movement in the direction of the insect, on the other hand, results in its 

 immediate flight. Few membracids respond quickly to stimuli of light or 

 heat; the hght from a mirror or the condensed rays of the sun as pro- 

 jected thru a lens have little effect on the resting insect if no other stimuli 

 are present. Rain causes the membracid to move to the underside of the 

 stem or leaf, but a strong wind merely causes it to cling more tightly to 

 its host without a change of position. 



