TWENTY-NINTH FRUIT-GROWERS' CONVENTION. 



161 



thing where the moths are abundant; for instance, in the neighborhood 

 of packing-houses. 



As to the time of egg-laying, there seems to be a great difference 

 according to the locality. In some places it is very evidently condi- 

 tioned upon the weather. One may find, for instance, upon a tree, the 

 majority of the eggs in about the same stage of development, indicating 

 that they were laid probably the same day. Apparently this evident 

 periodicity in the laying of the eggs is dependent upon the effect, upon 

 the moth, of weather conditions. Every one has noted that some even- 

 ings insects will be extremely abundant about electric lights, and that 

 possibly the very next night there will only be a stray insect here and 

 there. It is supposable that the weather condition which affects the 

 moths which we find about lights would also have an equally striking 

 effect upon the activities of the codling-moth and that unfavorable 

 weather would prevent the laying of eggs sometimes for days at a time. 

 This at least seems to be the most feasible explanation of the practical 

 immunity of one portion of the Pajaro Valley from ravages by the cod- 

 ling-moth. That portion of the valley between the city of Watsonville 

 and the sea is apparently free from these insects. In some orchards 

 the codling-moth has been introduced repeatedly upon fruit-boxes and 

 has been observable in some cases the succeeding year, but the uniform 

 testimony of the orchardists of that region is to the effect that this 

 slight attack never lasts longer than a single season. One of the char- 

 acteristic features of the climate of the Pajaro Valley are the fogs 

 which float in from the ocean with the afternoon winds, causing a chill 

 in the atmosphere at just the time of the day that the moth would 

 ordinarily be active. And the region where the greatest evident 

 periodicity in egg-laying Avas observed is immediately adjacent to the 

 immune area. Apparently, in this area showing periodicity in egg- 

 laying the conditions are such during most of the time that the moths 

 are prevented from flying, but now and then there comes a day in 

 which they can lay their eggs, so that these areas may be nearly as 

 badly infested with worms as though the weather was favorable all the 

 time. 



We have in California two classes of localities free from the codling- 

 moth: Those interior points, especially among the foothills, where young 

 orchards are isolated from other orchards and which have not yet 

 become infested with the codling-moth; and such areas as this part of 

 the Pajaro Valley, where apparently the proximity of the sea produces 

 a permanent immunity. Such permanent immune areas are found all 

 along the coast from the northern end of this State southward, certainly 

 at least to Santa Barbara County. Judging from the experience in the 

 Pajaro Valley, orchards but a short distance inland from the perfectly 

 immune area may be very seriously injured by this insect. 

 11 — F-GC 



