420 W. D. FUNKHOUSER 



of the imagination be made to resemble any peculiarity of the oak twig 

 on which the insects rest, and in fact they are very conspicuous on their 

 host. Likewise the Ceresas, perhaps the most widely distributed genus 

 in the basin, are plainly seen when in their natural surroundings, and the 

 two prominent suprahumeral horns do not in the least resemble plant 

 structures with which the insects are associated. The answer of the 

 natural selectionist might be that at some previous time such adaptation 

 had held, and this of course is unanswerable since we have no way of 

 knowing what host plants may have been the home of the insects in 

 bygone periods; but it is interesting to note that the genera Ceresa and 

 Telamona, which now show little protective resemblance to parts of 

 their hosts, are more numerous and apparently maintain an existence 

 with greater ease than do those species that show very excellent protective 

 resemblances. 



It is unnecessaiy to take up separately each of the local forms in this 

 respect. For each it is possible to suggest an explanation, reasonable 

 or otherwise according to the degree of imagination possessed. But 

 in general it must be said for the local forms, as for the family as a whole, 

 that such speculation merely lies in the realm of conjecture. 



The habits of the Membracidae afford a protection by no means 

 unimportant. The fact that they remain motionless for hours at a time, 

 pressed tightly into the axil of a leaf or the crotch of a twig, may explain 

 their escape from many enemies. Their habit also of remaining quiet 

 during that part of the day in which the birds are alert, and confining 

 their activities to the hottest parts of the day when other animals are 

 inchned to be at rest, has been suggested as tending toward their pro- 

 tection. The habits of both nymphs and adults of creeping around to 

 the other side of a branch when approached is no doubt purely protective. 



A most valuable and effective method of protection is the insect's 

 quick flight when disturbed. The sharp spring from the twig followed 

 by the erratic course thru the air is decidedly deceiving to the eye and is 

 doubtless an efficient defense against the attack of any but the most 

 active and keen-eyed enemies. In fact no enemy has been obsei^ved 

 to capture a membracid while the latter was on the wing. 



Finally, the hard pronotum and sharp spines of the thorax are doubt- 

 less sufficient protection against most foes. Very little of the soft ]:)arts 

 of the membracid's body is exposed, and the tough, often hairy prothorax 



