Biology of the Membracidae of the Cayuga Lake Basin 371 



In the case of the genus Ceresa the entire egg slit is made first. The 

 ovipositor is inserted perpendicularly and then gradually moved back- 

 ward during the process until it is almost parallel with the abdomen. 

 During the insertion of the eggs the ovipositor is repeatedly withdrawn 

 from the slit and forced back at a point slightly in advance of the last 

 incision (Plate xl, 2). 



Thelia hifnaculata makes the egg slit and inserts the eggs at the same 

 time. The ovipositor moves slowly thru the bark, forcing the tissues 

 apart and depositing the eggs in one movement. 



With a few species the ovipositor is withdrawn from the host after 

 each egg has been deposited, and reinserted for the next egg. This is 

 true of Enchenopa hinotata and for all of the species of Stictocephala 

 whose life histories have been studied. 



Entylia hadriana lays a number of eggs, then rests, then moves forward 

 along the same slit and deposits more — generally a different number — 

 then rests again, and so on imtil a complete row has been finished. 



The process of oviposition has been observed most commonly in the 

 middle of the afternoon, when the sun is the warmest and the temperature 

 the highest. It is usually noticed also on that side of the tree or plant 

 which is exposed to the most direct rays of the sun at the time when the 

 process is in progress, except in the case of Entylia hadriana, which 

 chooses the underside of the leaf. Wildermuth (1915:350) has observed 

 that in Stidocephala festina the eggs are usually laid at night or early 

 in the morning, and suggests that the insects avoid extreme tempera- 

 tures. This has not been found to be the case locally as the field records 

 show, but the fact that Wildermuth's observations were made in a region 

 of very different climatic conditions may explain the lack of agreement 

 of the data. 



The number of consecutive ovipositions made by one female varies with 

 the species but has not been greater than five in any species noted. The 

 average is not over three. In most cases the insect after depositing one 

 egg mass moves along the twig for a short distance and repeats the process 

 after a very short interval of rest. One female generally lays all her eggs 

 on one twig or on twigs very close together, and it has never been observed 

 that the insects move from one plant to another during the process. 



While ovipositing the insect is entirely occupied with her woi-k and 

 does not respond to external influences. She refuses to be disturbed and 



