Fulton, H. G.

English

Journal of the Entomological Society of British Columbia

44 ENTOMOLOGICAL SOCIETY OF BRITISH COLUMBIA, PROC. (1957), VOL. 54, DEC. 16, 1957 UNUSUAL DAMAGE TO POTATOES BY THE TWO-SPOrrED SPIDER MITE, TETRANYCHUS TELARIUS (L.), IN THE LOWER FRASER VALLEYl H . G. FULTON 2 Entomology Laboratory, Chilliwack, B.C. Ear ly ill .J ul y, 1956, it was obse rved t hat the tops of lat e Yetted Cem po-tatoes we re bruwl1ing alld dying uff in a 14-acre field at :-;ardis, nrit i ~h Co l-umbia.ll1\ est igat io ll sh()w eci that the damage was caused by hrge numbe rs (Jf the t \Vo-sputted mite , Telrallychlls le/Clrilfs eL. Y Infested areas were particularly Ilotic e;lbl e at th e edge o f the fie ld adjoining a ditch and hedge-row of weeds and brush. Late r in July and during August similar dam-age was fuund in potatu fleld s at Cole-brook and Cloverda le. Although this mite has been recorded as a pest o f potatoes in vVashington and Idaho, this is the first time to the writer 's knowledge that it has damaged pota-toes in British Columbia. Large populations of the mite were a lso ob-served on sweet corn, pole beans, and marigolds at di fferen t loca tions. 1. Contribution No, 3648, Ento l1loiog-y ])i\-ision, Science SCI-vice, Department of Agriculture , Ottawa, C anada. 2. ' f'echllicai Offi ce !". 1. lden tified b)' C. V. c. ~-r org-a ll. Entomology Laboratory. SUlllmerland, D.C. The fact u rs fa vouring the outbreak are Jl()t clearly understood. The sum -mer was general ly hot and dry but no reco rd s were set. However, general weather conditions Illust have been favourab le for the rapid multiplication of the Illites . A possible contl-ibutory factor is the widespread use of DDT to control the tuber nea beetle. Vari-ous researchers have shown that u se of DDT is followed by an increase in the abundance of mites. Some say that the natural predators are killed (Pickett, 1949); others claim that mites exposed to DDT lay more eggs (Hueck, 1955); sti ll othe r s state that the insecticide brings about changes in plant nutrition and composition (Klostermeyer and Rasmussen, 1953). The si tua tion is worth watch ing since one or more of the recently in-tl'oduced contl'ol pl'actices for other potato pests may [aYOllr increase of the Illite. References Pickett, A . D. A cntIquc o n ins ec t chemical control method s. Can. En\.. 81 : 67 -76. 19~9. Hueck, H . J. Thc population-dynamics of the fruit tre e red spiel er "ith special referen ce to the influence o f DDT. Proefschr. Rijkslluiv, Leidcn, 1~8 P[l., 1953. Rev. Appi. Erll . (A) 43: 340-342. 1955. Klostcrmeyer, E. C. and VI/. D. Ra smussen . The effect of soil in sec (i,ide (reatmcnts 011 mitc pOJlulation a nd damage. J. Econ. Ent. 46 : 910-9 12. 1953. The Wharf Borer in a Vancouver Branch Library In June, 1956, I was asked to investigate some beetle s which the librarian s of a hran ch library had found flyin g around thc premises and had tentatively identified h om litcrature as Nacc,.da me/anura (L.), the wharf bo rer. Th eir identifi cat io n was co rrect. In volume 43 of t he Proceedings of our Society, T publi sherl an article "An unusual record of the wharf bore r in buri ed piling", reporting that this beetle bred at tidewater in piling that had bee n covered by a slab of conc rete fo r thirty years. The branch library is a one-storey. 1500 sq uare foot building, loca ted on to p of a littl e hill with natural drainage o n al l s id es. There is no basement and o nl y small ventilat.or open-in gs in front, so thal most of tlie fl oo r is ove r a dead air space. In February, 1957, the library was closed fo r 10 days for re-pairs to the fl oo r and I was able to pro-cure half a sinkful of sodden black lumber which the carpenters had thrown out from underneath the floor. Some 16 N . me/allum emerged from this material in the course of the next six weeks. 

Unusual damage to potatoes by the two-spotted spider mite, Tetranychus telarius (L.), in the Lower Fraser Valley

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Unusual damage to potatoes by the two-spotted spider mite, Tetranychus telarius (L.), in the Lower Fraser Valley

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Journal of the Entomological Society of British Columbia