Cockle, J. W.

English

Journal of the Entomological Society of British Columbia

20 B. C. ENTO.\IOLOGTCAL SOCIETY A SWARM OF VANESSA CALIFORNICA AND SOME NOTES ON A SWARM OF PLUSIA CALIFORNICA By J. W . Cockle Comm encing on Jun e 17th of thi s yea r a very la rge numb er of V. ca1ifornica w ere t o be seen on th e lower slopes of the m ountain s round K ootenay L ake. It is u sua l to see a few hiberna ted specimen s of this buttedl y in th e ea rl y spring, ju st a s soo n a s th e wea th er is warm enoug h to p ermit th em to emerg·e from th eir w inter quarters, b ut what amoun ted to a large swann in th e midd le of Jun e was mos t unu sua l. A ll of th e specim en s ,,·e re yery fr esh and looked as if they mig ht be f reshl y em erged, but my suppos it ion was that they \y ere part o f a brood th at had hibern a t ed a t a ve ry hi g h a ltitude a nel co n sequently did not leave th eir ,,·inter qua rter s until t he snows had m elted in th e neig hbou r-hood in w hi ch th ey had hi bern a ted. Thi s suppos ition is back ed up by th e fa ct that th e 111 0untain s round I(ootenay Lake ri se to an a lt itude of ove r 9,000 fee t a nd th eir onl y know n fooel p lan t , Ceanothus sanguineus, groll·s mos t abund antl y up to nea r t he summits. A bout th e fir st week in }\ugu st th e new broo d began to m ake th eir a ppea ran ce a nel in a few days th ey ,,·ere to be seen in count less thou-sand s. not a lone round K oo tenay Lak e but ea st,,·ard ac ross th e mountain ran ge in th e va ll ey of th e Colum bia a nd westwa rd in to th e va ll ey of th e A rrow Lakes dist ri ct . Th e em erge nce seemed to r each it s zen ith about th e 1jth of Aug ust. at ,,·h ich t im e th ey ,,"e re eve rYI\"h ere; a long th e roads in th e afternoon th ey ,,· ere t o be seen settled on th e roadbed in su ffi cient numbers to a lm os t obsc ure th e g round. 1 kept a good lookout fo r any abe rrat ion s but none were seen, ,,·herea s in th e S" ·<Hm that ,,·as here in t he sum1l1 er of 1890 seve ra l di 1l1 o rphi c speci m en s. were captured by a co ll ector here; th cse a re, I beli e l"c, no,," in th e Ca ll1 brid ge Mu se um in En g land" T he tim e of t heir a rri l"a l and subsequ ent emergence shows that th eir entire lan"al a nd [lu pa l stagcs ,,"c re co mpl etcd in five week s ; thi s i" remark ab le a s th ose th at occur here o rdi na rily lI'i ll take from th e beg innin g o f :'IIa )" until .\ug us t to compl ete th e ir life-hi sto ry. I hal"c a lso to reco rd a s ll'a rm o f P1usia californica ,,"hich e1l1 erg ed a t t he end of Sep te1l1ber. The} werc much in ev id ence in th c afte rnoon and ear ly cI"cnin g- Ay in g Ol"c r t hc clol"e r, a s Ill a ny a s t ll"enty o r thirty m ig ht bc ta ken on th e clOl"e r bloSS01l1 S ,," ithin a space o f a square y ard. T huug h t hcy ,,"e re so pl e1l t iful in th c lie ld s , th e} \V cre very sca rce at lig h t. ,," hi ch is (Iu itc the rel"c r se o f th eir u sua l habit . It lI"as curi ou :-; th at P. californica ,,"a s so nUlll erous. ,,"hcll th c sca rcity o f a l\ oth er va ri e ti cs of Plu sias ,,"as so ma rked , th c onl y o ther species of t hi s genu s th a t occurrcd sparingly herc las t sumlll er was viridisignata, a l\ othe r m Clll bers o f t hi s fa lllil y werc con spicuous by th eir ab sence, not a s ing le spccim en lI"a s tak en here by eith er of th e co ll cc tors. 21 As P. ca1ifornica w hen num erou s ha s proved a bad pes t amongst the alfalfa ficld s, it remain s to be seen if th ey will pass the winter in suffi cien t numbers t o mak e them a bad pest in the coming summer. R egarding the eco nomic valu e of reco rd s of swarm s of in sec t s, it may be well t o conclude thi s art icl e \\·ith a few no te s. V. californica feeds only on the Ceanothus which, \vhen attacked by a swarm , is comp lete ly defolia ted, area s of man y acres have be en obse rved wh ich had been entirely stripped of every vestige of fol iage, and it is not unu sua l to find the pupee su spended from the leafles s branch es . I have seen in stances where th e pupee hun g in rows (with a n inter vening space in some cases not exceeding one in ch ) right a long th e branches . T he fact that V. ca1ifornica on ly feeds on the Ceanothus form s a n exception t o the ma ny insects which fav our this shrub as a food p lant, most of the oth er in sect s w hi ch feed on it w ill attack th e foliage of th e apple trees which have superseded th e \I·il d bru sh on th e clea red land. A no ther fa ct t hat \I'a s obse rved after th e swar1l1 of 1890 wa s th e alm ost entire ab sence of th e in sect for severa l years fo llo wi ng . Th is year swarms of th em are hibern a ting. D uring January I had occasion t o remove som e lumber \I'hich had been pi led in the roof of th e ba rn and foun d thousa nd s of th em packed in bet ween th e stack s of boards; it would have been easy to fill a (Juart m easure w ith them. As regard s P. ca1ifornica 1 have reason to beli e ve t hat a ll th e P1usias that occur in th is secti on of Briti sh Co lumbia are s ing le brooded. Ca1ifornica hiberna tes a nd in th e spring o f 1914 was g reat ly in ev idence fl y ing round the fruit tree b lo0111 , to which 1 beli eve th ey acted as good pollinato rs. I wou ld like t o refer to a pam phl et iss ued by the E ntomological Department, being a r e-print o f an arti cle by l\lr. A rthur Gibson which was publi shed in th e Agri cultura l Gazette, entitl ed "The A lfa lfa L ooper," in w hi ch the statem ent is made th at th ere a re probably t wo di stinct brood s each yea r ; this state ment I be lieve to be inco rrec t. I t is a fac t that fr eshl y em erged specim en s may he foulld durin g July, but it is al so ve ry probable that some specimen s lIlay ha ve been confu sed with Pseudogamma. T hese t wo species are so much a like t hat a correct ident ificat ion is sometim es diffi cu lt. Pseudogamma fli es during Jul y , A ugust a nd September and passes the winte r in th e larva l stage. I have n eve r seen a hi berna t ed spec imen of it. I have reco rd s of Ca1ifornica from .J uly to th e foll owing ] une, bu t a ll th ose ta ken in the sp r in g are hi bern ated ; th e records of Pseudo-gamma run from Jul y to October , w it h no record of any hibernated spec im en s in th e followin g' spr ing . I have no reco rds of th e capture of hibernated sp ecim ens of a ny of th e fiftee n species of P1usia t ha t occur here, except a s stated in t he ca se of Californica. 

A swarm of Vanessa californica and some notes on a swarm of Plusia californica

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A swarm of Vanessa californica and some notes on a swarm of Plusia californica

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Journal of the Entomological Society of British Columbia