On the identity of Culex pallidohirta

OF WASHINGTON, VOLUME

_XII, 1910. 81

ON THE IDENTITY OF CULEX PALLIDOHIRTA.

[Diptera; Culicidae.]

BY HARRISON G.

DYAR AND

FREDERICK KNAB.

Grossbeck described Culexpallidohirta ⁱⁿ 1905 (Can. Ent., xxxvii, 359) from

two

female specimens ^bred

May

^{5 from}

pupae ^{collected in}the

Orange

Mountains,

New

Jersey.

The

supposed^{speciesis very}unusual inappearance, the whole dor- sal region ^ofthe

abdomen

being covered with _grayish ^silvered

scales.

One

of the typespecimens^{is in the} U. S. National

Museum

and hasbeenoften

examined

_byus. It is an _Acdes, and it

would

seem as if otherspecimens^should have occurred

among

^the early spring collecting during ^{the last five} years

ifthe _species were _really valid. But none have been found.

We

have been suspicious of the _species for this reason, and also forits freakish appearance, but have been hithertounable to suggest any plausible explanation.

We

have, therefore, been obliged unwillingly ^{to list} Acdespallidohirta ^{as a valid} species

known

_{only by} the two type specimens.

Recently, however, lighthas been

thrown upon

^{the matter} from amost unexpected quarter.

A

lotofmosquitoes ^{in alco-} hol were submitted to us for determination, ^collected by ^a correspondent ^of the U. S. Public Health and Marine_Hospital Service in Malaga, Spain.

Two

_species werecontained in the sending, which

we

were enabled to positively identify by ^the male genitalia as Cnlexpipiens Linn, and Acdes_{calopus.Meig.}

Of

the latter, several specimens were ^taken from the alcohol and_dried, when, ^to our surprise, three females exhibited the

abdomen

suffused withdull silvery ^all over the dorsum, ^while

two

maleswere normally marked. These females _possessthe peculiar scalingon the clypeusabsolutely diagnostic ofthe _spe-

cies, even

when

the thoracic markings^{arelost,butof the}lyre-

shaped

marking

^{there are distinct traces in one} specimen, though on ^a very light ground.

The

_{palpi arebroadly} silver- scaled at the _tip; the _legmarkings^arenormal; ⁱⁿonespecimen the

abdomen

^is silvery gray on the _sides, but the lateral spots

still

show

as abrightersilvery; inanotherthere are

some

black scales _laterally, especially around these _spots, most

numerous

on the_posteriorsegments.

The

identity ofthe_speciesis,there- fore, perfectly obvious in this _case, while the conclusion is justified that the silvery suffusion of the

abdomen

^is not a specific character in Acdes. Moreover, ^{it is}not even _truly varietal, butin the nature ofan aberration or a freak.

Applying ^{thisconclusion to}Aedespallidohirta^{> it is} easy ^to recognize ⁱⁿ thesupposed species merely ^{a freakish} specimen

82

PROCEEDINGS ENTOMOLOGICAL

SOCIETY

of Acdes fuscus O. ^{S. In} fact,

we

are able to detect in our specimen ^ofpallidohirta the white lateral lineonthe

abdomen

characteristic offuscus.

It isprobable ^{that this} silvery scaling

may

^{occur on other}

partsthan the abdomen, ^forinstanceonthe _{legs, in}whichcase Acdesnivitarsis Coq. ^will be seen to be only an aberrationof Acdes canadensis Theob., as Dr.

Ludlow

formerly suggested to us.

We

^are _ignorant of the cause of thispeculiar variation. ^It cannot be produced by ^{thefluid in} whichthe specimens were preserved, because the malesof calopns from_{Spain, preserved}

in the

same

bottle with the females, were not thus _affected, and because Mr. Grossbeck's typeof pallidohirta

was

_{not put}

in fluid. It cannot be dueto the specimens having been wet on emergenceⁱⁿ the breedingjar, because thespecimens from Spain were ^{not bred,} but captured,

some

_havingbloodin their stomachs. It seemsdoubtfulwhetherthe chemical contentsof the water ^is the _{cause, for} while pallidohirta and nin'tarsi's

both

came

from _pools on the mountains of

New

Jersey, the aberrant calopns could only have bred in water-vatsor other artificialreceptaclesⁱⁿ Malaga, Spain. Moreover,normal

exam-

ples of canadensiswerebredfromthe

same

_{pools as}\.\\z

pallido- hirta, at the

same

time, as Mr. Grossbeck states, and these should have been similarly affected ^if the composition ^of the water were the cause.

We

can only suggest theaction of coldupon^thenewly formed pupa?.

W. H. Edwards

and others have

shown

that the effect of cold

upon

^the newly formed _pupa? of Lepidoptera ^is to produce ^{a suffusion of the colors, the light colors being} extended and_enlargedattheexpense^ofthedarkones, asⁱⁿthe peculiar form calverleyi ofPapilio^asterias.

The

similarsuf- fusion of the white abdominal or tarsal bands of the Acdes might produce ^the peculiar^effect noted.

That

this isa _possi- ble explanation ^issupported

by

^{the factsthat} the calopnsfrom Spain were takenⁱⁿ December, ^{while the}

New

_Jersey ^insects

werebred from _earlypupae inthe spring^{of 1905.}

The

writers havecauseto

remember

the late snows and cold ofthat spring, which

hampered them

ⁱⁿtheir collections ofthe_earlymosquito larvae in Massachusetts andnorthern

New

York.

That

the Aedes canadensis in the

same

_pool were not _similarly affected

by

^{the cold, aswere}the fuscus^intoapallidohirtaform,

may

^be

explained

by

^their having pupated ^{later, after thecold spell.}

Mr.Grossbeckstates that they emerged ^laterthan \btpallido- htrta.