ECONOMIC ZOOLOGY ENTOMOLOGY. 261 



Attempts to remove the pest by trimming off all infested canes as soon as 

 they began to show signs of attack resulted in the infestation of from SO to 90 

 per cent of ail young shoots the following spring. It is thought that the pest 

 may best be dealt with by crushing the eggs with the thumb or finger by 

 slight pressure over the discolored area where they are deposited. 



On the feeding: habits of Pimpla (Itoplectis) conquisitor, F. A. Johnston 

 {Jour. Econ. Ent., 6 (1913), No. 1, pp. llt^-lltl). — The author reports observa- 

 tions of the feeding of this ichneumonid pai-asite at punctures made by its 

 ovipositor in larvae and pupse of Autographa brassiccp. 



The red spider on hops in the Sacramento Valley of California, W. B. 

 Pakkeb (f7. S. Dept. Agr., Bur. Ent. Bui. Ill, pp. Jfl, pis. 6, figs. 9).— This 

 report of investigations, commenced on January 1, 1911, and extending over a 

 ])eriod of IS months, is based on ob.servations made in the hop fields in all parts 

 of the Sacramento Valley, where spraying experiments weie conducted on both 

 a large and small scale. 



This pest was reported in injurious numbers in hop fields at Wheatland, 

 Yuba County, Cal., in 1902, since which time it has caused some injury to hops 

 in the Sacramento Valley every year, and in 1910 the hop crop was seriously 

 injured in many localities. It has also been a source of injury in the State of 

 Washington and at Agassiz, British Columbia. The attack of these mites re- 

 sults in the leaves becoming speckled, turning yellowish, and when severely 

 injured drying up and falling to the ground. The mites were not observed to 

 feed upon hops antil they were full size. The decrease in the vitality of the 

 vine, which is the direct result of the attack by mites, produces a premature 

 ripening of the hops. 



The eggs of Tetranyclius himacitlatus, the mite concerned, are deposited singly 

 among the webs and upon the underside of the leaves. During February, 1912, 

 the incubation period at Berkeley, Cal., was found to be from S to 10 days; 

 during Mny the period was from 5 to 10 days, with an average of 7.2 days, 

 while in July, iOll, it was only 4* days. The length of the larval and nymphal 

 periods was found to vary from S to 16 days, according to the temperature. 

 Observations by the author show that parthenogenesis occurs with the i"ed 

 spider. The winter is passed upon wild plants in and around the hopyards. 

 In experiments conducted on sheets of paper, the surface of which corresponds 

 fairly well to that of the hop vine, it was calculated that an average female 

 mite is capable of covering 213 ft. of vine surface during a period of 10 hours. 

 In 1910 the first mite observed upon a hop vine was found April 21 in the 

 center of a yard near Sacramento, where it was surrounded by S eggs and pro- 

 tected by a small amount of dusty web. The mites were found to appear 

 simultaneously in various parts of the hoi) fields and did not invade the 

 yards from along the edges as was formerly supposed to be the case. 



This mite has a remarkiibly large number of host plants, belonging to a 

 wide range of families, including glabrous and hirsute plauts. It is in fact 

 nearly omnivorous as far as plant life is concerned. 



Of the predaceous enemies the small anthocorid bug TriphJcps tristicolor is 

 said to be the most numerous. Several small lady beetles, including Scynniiis 

 nanus, S. marginicoUis, and Pcntilia sp., were found to prey upon this red spider. 

 Chrysopa calif ornica in the larval stage is said to have been very abundant 

 during July and to probably have done more good than all the rest of the 

 predaceous insects together. 



The I'emedial experiments here reported in detail have led to the following 

 conclusions : " The mites on hops are not affected by any form of dry sulphur, 

 but are readily killed by several contact insecticides, the chf,apast and most con- 

 venient of which are flour paste (8: lOOi or a combination of lime-sulphur, 36° 



