88 



the larva, leaving a single egg on it, generally near the head. One 

 larva frequently bears several eggs or immature larvae of the parasite 

 at the same time. The incubation period in New South Wales during 

 the winter lasts from six to seven days, at a temperature varying 

 between 48° and 65° F. In the Hawaiian forest in summer this period 

 will doubtless be much shorter. The larva lies throughout its develop- 

 ment on the body of its host, practically inactive, imperceptibly 

 puncturing the skin and sucking the body juices. The growth is 

 very rapid, the host shrinking meanwhile, until it collapses entirely. 

 The larval stage occupies from 9 to 11 days during the New South 

 Wales winter (at 48-70° F.). When mature, the larva creeps away 

 for a short distance in the hollow fern stem and there spins a white, 

 silken, cylindrical cocoon. Pupation takes place several days after 

 the cocoon is completed and lasts 18 or 19 days. The adult emerges 

 by a circular hole cut through the wall of the fern stem. Mating may 

 occur immediately after emergence, and oviposition has been observed 

 four days later, at cool temperatures. The greatest number of well- 

 developed eggs found in any female was twelve, but the adult is very 

 hardy and long-lived ; females kept in a test-tube were still alive 

 after 91 days. 



The complete life-cycle of the parasite in a New South Wales winter 

 requires about 44 days ; this in Hawaii will be somewhat less, especially 

 in summer. The life-cycle of 5. fidvitaysis in Hawaii occupies from 

 105 to 135 days. In view of the hardiness of the parasite, and its 

 short life-cycle compared with that of its host, a rapid reduction in 

 the numbers of the weevil can reasonably be expected, particularly 

 as the parasite flourishes in dark, wet forests in New South Wales, 

 and similar conditions obtain in Hawaii where the weevil has been 

 increasing. 



Leach (B. R.) & Thomson (J. W.). U.S. Bur. Ent. Experiments in 

 the Treatment of Balled Earth about the Roots of Coniferous Plants 

 for the Control of Japanese Beetle Larvae. — Soil Science, Baltimore, 

 Md., xii, no. 1, July 1921, pp. 43-61, 7 tables, 2 plates. [Received 

 19th December 1921.] 



The experiments described in this paper were undertaken in 1920 

 as a result of quarantine measures prohibiting the shipment of soil 

 or coniferous plants with soil about their roots from an area in New 

 Jersey infested with Popillia japonica (Japanese beetle). Endeavours 

 were made to determine the comparative value of certain gas-producing 

 compounds against this pest and their effect on the plants concerned. 



The author's conclusions as a result of the experiments are that 

 certain compounds in solution capable of producing a gas insoluble 

 or only slightly soluble in water are toxic to the larvae. Of these com- 

 pounds carbon bisulphide, thymol and mustard oil are slightly 

 soluble in water, and sodium sulpho-carbonate and sodium ethyl - 

 xanthate are readily soluble. These compounds on being decomposed 

 by organic acids yield carbon bisulphide, the killing agent. The former 

 solutions readily kill the larvae when removed from the soil, but are 

 ineffective against soil-balls containing larvae, as the soil only adsorbs 

 that portion of the compound incapable of destroying the larvae. 

 When the latter compounds are used in relatively concentrated solutions, 

 the portion of the compound toxic to the larvae remains free in 

 the soil. 



