28 



THE GKAPE HOOT-WORM. 



Table III. — Summary of oviposition experiments, recorded in Table II, showing the final 

 average, maximum^ and minimum, of egg deposition by individual female beetles in 

 captivity, at North East, Pa., 1909. 



Observations. 



Average. 



Maximum. 



15.9 



24 



4.4 



9 



3.6 



15 



24.0 



61 



112.0 



263 



Minimum. 



Number of days previous to first oviposition 



Number of times of oviposition 



Number of days between ovipositions 



Number of eggs per cluster 



Number of eggs per female 



In Table V (p. 30), giving records of experiments with a large 

 number of beetles in stock jars, where only the minimum length of 

 time could be verified, this feeding period is shown to have covered 

 from 9 to 10 days. Feeding is continued for almost the entire length 

 of life of the beetle, and it has undoubtedly a direct bearing upon the 

 number of eggs deposited. 



MATING AND ITS BEARING UPON EGG DEPOSITION. 



Mating of beetles has been observed a few days after their emer- 

 gence. It has been found to take place several times before the first 

 egg deposition, the day previous to oviposition, and also after each 

 oviposition. Repeated mating, however, is not essential in bringing 

 about further egg depositions, as shown in one instance under obser- 

 vation (Table II, jar No. 13). In this jar the male and the female 

 beetles were confined together shortly after emerging. Mating took 

 place July 27, 28, and 30. The male beetle escaped August 5, yet 

 oviposition by the same female occurred on August 7, 11, 14, 19, and 

 23 without further mating. 



PROCESS OF EGG DEPOSITION. 



As the time of egg deposition approaches, the female beetles cease 

 feeding for a day or two and become sluggish and somewhat inactive. 

 They generally seek the shady places and are at this period to be 

 found on the canes of the vines, where they are less easily detected. 



The eggs are deposited almost entirely under the loose bark on the 

 canes and trunk ; very rarely, however, they are placed on other parts 

 of the vine. The female inserts the eggs beneath the loose bark by 

 means of the protrusible ovipositor (fig. 11, e) and places them side 

 by side in a cluster of a single layer. An adhesive substance, secreted 

 by the female, glues the eggs together, and the entire mass is fastened 

 either to the cane or to the inner surface of the loose bark (PI. I, figs. 

 3, 4). Individual female beetles have been observed to move along 

 the canes in search of suitable places for egg deposition. In this 

 process the hind end of the body touches the cane, and as the insect 

 slowly passes along the ovipositor is inserted into the cracks or crev- 

 ices, apparently testing the fitness of these places for egg deposition. 

 A female beetle is shown in Plate I, figure 1, photographed in the act 

 of oviposition. 



