656 EXPERIMENT STATION RECORD. 



The authors point out that citrus fruits are not the favored host fruits of 

 V. capiiata that the earlier writers thought. " While grapefruit, oranges, lemons, 

 and many limes may become quite badly infested with well-grown larvae if 

 allowed to remain on the tree long after they become sufficiently ripe for the 

 market, nature has so well equipped them to withstand attack that larvae 

 are seldom found in their pulp until they are much overripe. Oranges and 

 grapefruit are generally eaten and found uuinfested if gathered as they ripen." 

 The oil of the cells ruptured in the formation of the egg cavities kills a large 

 percentage of the eggs and newly-hatched larvae. " LarvtB that succeed in en- 

 tering the rag from the egg cavity are able to reach the pulp in astonishingly 

 small numbers because of the iraperviousness of the rag. It is only the per- 

 sistent attack of successive lots of larvae hatching from different batches of 

 eggs laid in the same puncture in which the oil has become inoperative that 

 finally breaks down the barrier between the young larvae and the pulp. 



" The Mediterranean fruit fly is quickly affected by low temperatures. A 

 temperature of about 56° F. has lengthened the time required by the fly to pass 

 from the egg to the adult stage from 14V2 to 91 days. A temperature ranging 

 from 50 to 55° will either seriously check development or kill large numbers 

 of the immature stages of the fly. The winter monthly mean temperatures of 

 California and Florida are so similar to those of the citrus regions of southern 

 Spain and Italy and of Sicily that it is to be expected that the fruit fly if in- 

 troduced to the mainland would not become a serious pest to Citrus spp. It 

 happens that the very cold temperature necessary to bring citrus crops to that 

 degree of perfection in which they are most susceptible to fruit fly attack like- 

 wise renders the fly so inactive or sluggish that it may be disregarded as a 

 pest for that period of the year. 



" In addition to the assistance of adverse climatic conditions during that 

 part of the j^ear when tliey are most needed to protect citrus crops, the growers 

 of California and Florida are still further protected — and most admirably so — 

 from attack by the very scarcity of wild host fruits that can not be destroyed. 

 It will be found a practicable undertaking to remove such a number of noncitrus 

 host plants at present growing about commercial citrus orchards that the suc- 

 cession of fruits in which the Mediterranean fruit fly can breed during the 

 large portion of the year when citrus fruits are unavailable for attack because 

 of their greenness will be reduced to a minimum, if not entirely done away 

 with. It is under conditions such as can be secured in California and Florida 

 that the excessive mortality occurring in the rind will become a valuable factor 

 in preventing infestation or establishment of the pest, as each fruit will in 

 reality become a trap for stray females. The scarcity of host fruits will also 

 make spraying with poisoned baits a practical undertaking, should it become 

 necessary to resort to artificial methods of control." 



A bibliography of 7 titles relating to the subject is appended. 



[Serious outbreak of Haltica foliacea] (New Mexico Sta. Rpt. 1914, P- 82). — 

 An outbreak of this fle;i-beetle upon grapes and young fruit trees is said to have 

 been checked through the use of powdered arsenate of lead applied at the rate 

 of 1% lbs. to 50 gal. of water. This mixture is said to keep the beetles off the 

 foliage for the most part and to prevent damage if applied in time. 



Observations on the life history of Agrilus bilineatus, R. N. Chapman 

 (U. S. Dept. Afff., Jour. Agr. Research, 3 (1915), No. 4, pp. 283-293, pis. 2).— 

 It is stated that at the present time the two-lined chestnut borer (A. bilineatus) 

 is commonly associated with the death of many oaks (Quereus alia, Q. waero- 

 earpa, Q. niljra, and Q. cocciiwa) in the southern part of Minnesota. In the 

 neighborhood of St. Paul aud Minneapolis large numbers of oaks, many of them 



