BULLETIN 195. CALIFORNIA GRAPE ROOT-WORM. 11 



LIFE HISTORY AND HABITS. 



The Egg. The eggs of this beetle are laid usually in crevices beneath 

 the inner layers of bark on the old wood. They are not confined to last 

 year's wood, as seems to be the case with its eastern ally, but are laid 

 anywhere on the stump of the vine above four or five inches from the 

 ground. ' "With the California system of pruning, there is of course 

 little of last year's wood left on the vine, and the bark on this is too 

 smooth to offer the most suitable situations for egg laying. Indeed, 

 during the past season we found no eggs on last year's wood, but all 

 on the older part of the stump, which was covered with two or three 

 layers of old bark. In some cases, where the bark was in close contact 

 with the wood, it was hard to explain how the beetle got beneath the 

 two or three layers to deposit its eggs. In nearly every case they were 

 certainly well protected from most enemies and out of reach of any 

 spray. 



The eggs are laid in clusters of from four or five to twenty-five or 

 thirty; usually where the smaller numbers were found the crevice in 

 which they were deposited would not furnish room for a larger number. 

 Where there was plenty of space the number ranged from a dozen to 

 thirty. The most common numbers counted in the many clusters exam- 

 ined ranged from ten to twenty. 



The eggs in the cluster may be irregularly arranged or somewhat in 

 the form of a concentric ring, the particular arrangement depending 

 probably upon the space in which they are deposited. Where there was 

 plenty of room the eggs were sometimes well scattered, extending over 

 a diameter of a quarter of an inch or more. In other cases a pretty 

 well defined concentric arrangement was found. Occasionally, a small 

 crevice would be found with but two or three eggs. 



Number. The largest number we succeeded in .getting a single 

 female to lay in our breeding cages was seventy-nine. These were laid, 

 at three different intervals, extending over a period of about one month. 

 Others laid but a single cluster of from fourteen to twenty and then 

 died. The same insect in France, according to Mayet, 1 lays in the 

 neighborhood of thirty eggs either singly or in patches on the under 

 side of the leaves. This number is probably simply an approximation. 

 The fact, if it is a common occurrence, that they are laid on the under 

 side of the leaves, is the most striking difference between the habits 

 in California and in France. We have had some eggs laid on leaves 

 in our breeding cages when there' was nothing else for them to oviposit 

 on, but we never found any indication of this habit in the field. 



From our breeding cage experiments and field observations we are 



1 Insectes de la Vigne, p. 308. 



