Rare Invertebrates of the South Okanagan by akgame


                                                                   of the South
                                                                  The endangered invertebrates
                                                                        of the south Okanagan
                                                                       are at risk because their
                                                                         ecosystems are at risk.

Province of British Columbia Ministry of Environment, Lands and Parks
                                              The diversity of                              that visit our picnics. Velvet ants are
                                              invertebrate communities                      common, too. These are actually wasps
                                              in the south Okanagan                         with wingless females that look like big,

                                                    e also don’t know how many in-          red, furry ants as they scurry around
The diversity of                                    vertebrates can be found in the         looking for bee nests to lay their eggs in.
invertebrates                                       dry, warm lowlands of the south         Spider-hunting wasps are also common

     here are many, many different kinds            Okanagan and Similkameen val-           and diverse – the most striking of these
     of terrestrial and freshwater inverte-   leys, but we can estimate that perhaps        is an unnervingly large, black species
     brates in British Columbia. If we        15 000 species live there. Although           with fire-coloured wings, which hunts
     went through all the reports and         many of these are common and wide-            the big ‘trapdoor’ spiders of the
lists that have been published over the       spread, some are confined to the dry           grasslands.
years, and peered through the museum          grasslands of the southern Interior –
drawers filled with specimens, we would        and there are literally hundreds that are     Alkaline lakes
be able to list 20 000 to 25 000 species.     found nowhere else in the province.           In some of the sagebrush basins lie lakes
But when all the surveys are complete         These are inhabitants of the Great Basin      ringed white with drying carbonate and
and all the specimens described and           grasslands and wetlands, which extend         sulphate salts. These alkaline flats are
identified, the total species count            only a few, narrow fingers north into          home to another unique community of
will probably be about 40 000 to 50 000       Canada.                                       invertebrates. Tiny ground beetles and
– about 100 times the number of species                                                     brilliantly coloured tiger beetles hunt in
of birds! Most of these invertebrates are     The shrub steppe                              and around the mud cracks, and busy
arthropods – insects, spiders and their       The hot, dry grasslands and shrublands        little shore bugs and great flocks of tiny
relatives – but molluscs, rotifers,           that remain in the south Okanagan and         shore flies move along the water’s edge.
tardigrades, and various worm phyla           Similkameen have an invertebrate              Brine shrimp and specially adapted spe-
also contribute to the total.                 fauna quite unlike that of the wetter,        cies of dragonflies, damselflies, beetles,
    This diversity of species translates      forested parts of the province. Sun-lov-      and water boatmen bugs paddle and
into a diversity of essential ecosystem       ing insects abound. Big, black darkling       crawl through the clear water.
jobs that these invertebrates perform.        beetles clamber across the sandy soil;
Many insects, including bees, flies,           rotund, fuzzy bee flies with patterned         Wetlands and riparian woodlands
butterflies                                           wings hover everywhere; colour-        In the valley bottoms, dry grasslands
and beetles,          Perhaps                   ful and not-so-colourful butter-       give way abruptly to a narrow band of
are key play-                                        flies visit spring flowers; grass-       moist woodlands along the streams,
ers in pollina-
                               species of            hopper wings crackle in the hot        marshes and lakes. These are home to all
tion. As a invertebrates live                        air; bristly robber flies buzz men-     the diverse invertebrates of lush woods
critical com-                                        acingly by; and in the warm eve-       – shade-loving flies, moths, wood-bor-
ponent of the
                          in the South               nings, scorpions scramble out          ing beetles, and many others. In the
food chain,                  Okanagan                from under flat rocks and the           warm, rich wetlands themselves are spe-
invertebrates                                        songs of crickets fill the dark void.   cial communities of dragonflies, diving
provide food
                              lowlands.               The group of insects that prob-       beetles, backswimmers, snails, mussels
for other ani-                                       ably symbolizes the hot shrub          and clams.
mals. Earthworms and other soil-              steppe the most, however, are the Hy-
inhabiting creatures help to create           menoptera – the bees, ants and wasps.         Why are invertebrates
productive soil. Many plants are              An astounding number of wasps hunt            at risk?

dependent on fungal associations              across the sunny meadows, especially              espite our general ignorance of in-
with their roots and invertebrates            where sandy soil makes digging nesting            vertebrates, we can say that the en-
are important as dispersers of fungal         burrows easy. Many species of several             dangered invertebrates of the south
spores. The many predacious and               families of ‘sand wasps’ live here – some         Okanagan and Similkameen valleys
parasitic invertebrates are vital in          red and black with long and slender           are threatened not by direct exploita-
the control of unwanted plants and            bodies and thread-like waists; some           tion, but by loss or degradation of their
other invertebrates that humans               banded with yellow and black, resem-          habitats. They are at risk because their
consider pests.                               bling the (unrelated) yellowjacket wasps      ecosystems are at risk.
   The rich soils of the grasslands          wetlands and dry uplands between
are a valuable agricultural resource,        Oliver and Osoyoos Lake. Only two tiny
and have been                                       ecological reserves exist in the
ploughed and ir-        Many species                south Okanagan, one of which
rigated to pro-                                     has burned completely, illustrat-
duce tree fruits,
                        are restricted              ing the need for a larger, more
grapes, and veg-        to ecosystems               comprehensive conservation              Western Ridge Mussel
etables. Pesticide                                  program in the valley.                  Gonidea angulata (Lea)
use has probably
                               that are                Various government agencies          This freshwater mussel (Order
had a great im-            themselves               and public organizations                Unionoida) is known in Canada only
pact on native in-                                  have tackled this problem by            from the main, valley bottom water
sects living in
                         endangered.                forming the South Okanagan              bodies from Penticton south. There
and around agri-                                    Conservation Strategy (SOCS).           have been few searches for it, and the
cultural areas. Heavy grazing has altered    SOCS coordinates activities in research,       only recent records are from the
the plant composition of grasslands and      land acquisition and habitat manage-           Okanagan River at Okanagan Falls,
has undoubtedly changed their inverte-       ment.                                          Vaseux Lake and Osoyoos Lake. The
brate communities as well. Recreation                                                       unionid mussels – the family that the
use, especially off-road vehicle traffic,     Rare invertebrates in                          western ridge mussel belongs to – are
has also damaged grasslands. In the val-     the south Okanagan                             very sensitive to environmental changes
ley bottoms, streamside woodlands            and lower Similkameen                          and consequently have a high percent-

have been cleared and converted to hay             s of 1994, 23 invertebrates are          age of endangered species within their
meadows.                                           known only from this small region        ranks throughout North America.
   Humans continue to flock to this re-             in the world and an additional 75
gion to enjoy its fine climate and, as cit-         occur nowhere else in Canada. As
ies expand, wetlands are drained and         mentioned earlier, of course, our
filled, and the dry benchlands paved and      knowledge of invertebrate ranges and
developed into suburban subdivisions.        status is poor, and new, intensive sur-
In the early 1950s, the Okanagan River       veys are needed to further clarify the sta-
was channelized and dyked, altering          tus of many of these animals. A provin-
forever the water flow and natural                                      cial report has
flooding regime that created the              Twenty-three named this area                   Parowana Tiger Beetle
marshes and lush riparian wood-                                                             Cicindela parowana Wick.
lands along its course.
                                             invertebrates one of the two
                                                                       highest priority     The Parowana Tiger Beetle (Order
   Today, only about 10 percent              are known                 areas for such       Coleoptera) dwells on alkaline flats
of the south Okanagan grasslands
remain in a relatively natural state,
                                             only from this surveys. our  Despite
                                                                                            where, as its name suggests, it ambushes
                                                                                            and consumes other invertebrates. In
and only about 15 percent of the             small region scanty knowl-                     Canada it is known only from Ok-
valley’s wetlands still exist. Pro-
tected areas and other areas man-
                                             in the world. edge, up listscan
                                                                                            anagan Falls, Oliver, and Penticton. It
                                                                                            hasn’t been seen recently in any of these
aged for wildlife are few and cover                                    invertebrates that   areas, and the Penticton site has been
less than 3 percent of the southern val-     are almost assuredly threatened or en-         destroyed by housing developments.
leys. Most are concentrated around           dangered in these valleys. These are spe-
Vaseux Lake, where BC Environment,           cies that are relatively large and obvious     Vivid Dancer Argia vivida Hagen
BC Parks, the Nature Trust of British        but still rarely seen or collected, and that   In southern British Columbia, this
Columbia, and the Canadian Wildlife          are restricted to ecosystems that are          lovely damselfly (Order Odonata) lives
Service all hold lands for the conserva-     themselves endangered. From this sort          around spring-fed pools and streams in
tion of wetland, grassland, rocky bluff      of list, we have chosen ten representa-        a very few, scattered localities, mostly
and dry forest ecosystems. The recently      tives from different invertebrate groups       associated with hot springs. Most of
created South Okanagan Wildlife Man-         and from a range of endangered habi-           these habitats are vulnerable to develop-
agement Area protects riverside              tats. Their stories follow.                    ment, and the damselfly populations are
                                                pions and shun the sunlight, preferring       later. Don’t confuse this mantid with
                                                to hunt at night. They live in sandy, dry     the much larger Praying Mantid, which
                                                areas, hiding under stones or in shallow      was brought to the Okanagan from
                                                burrows during the day. They are arach-       Ontario to control grasshoppers. This
                                                nids, relatives of spiders and scorpions,     species, originally introduced to eastern
                                                but are easily recognized by their large      North America from Europe, comes in
                                                heads and massive jaws (chelicerae),          brown and green forms and is fully
threatened. In the South Okanagan only          which they use to capture and crush           winged in both sexes.
two sites are known; both are small             their invertebrate prey. We know hardly
rangeland streams originating in cold           anything about the six species that are
springs, and both are disturbed by cattle       known from the south Okanagan – in
or horses. The aquatic larvae cling to the      fact, three of these species have been dis-
undersides of stones and roots in the           covered only recently and have not yet
small, trickling streams and muddy              received official, scientific names!
pools. The adults rest on stones or bare
earth nearby, or make low foraging
flights after small insect prey. Females                                                       Apiocerid Fly
lay eggs in aquatic vegetation, often sub-                                                    Apiocera barri Cazier
merging themselves in the process.                                                            This fly is the only member of the Fam-
Meanwhile, the males protect their                                                            ily Apioceridae (Order Diptera) occur-
mates from the attentions of other                                                            ring in Canada, where it is restricted to
males by retaining their mating hold on                                                       the southern Okanagan Valley. In field
the female’s thorax and standing stiffly                                                       guides, members of this family are usu-
at attention.                                                                                 ally called “flower-loving flies,” but re-
                                                Ground Mantid                                 search shows that Apiocera species, at
                                                Litaneutria minor (Scudder)                   least, hardly ever live up to this name.
                                                Mantids (Order Mantodea) are car-             They inhabit sandy, arid and semiarid
                                                nivorous insects distantly related to         habitats, and most flies observed never
                                                grasshoppers. They are easily recog-          visit flowers, but rather are found run-
                                                nized by their long, slender, neck-like       ning on the ground, especially near the
                                                thorax and grasping front legs. The           sparse vegetation, where they may feed
                                                Ground Mantid is the only mantid na-          on honeydew beneath aphid-infested
Sun Scorpion                                    tive to Canada. In this country it is         plants. They are often seen drinking
Eremobates gladiolus Muma                       known only from the dry grasslands of         from damp sand with their sponge-like
Sun scorpions (Order Solpugida), de-            the extreme South Okanagan near               mouth-parts. The carnivorous larvae
spite their common name, are not scor-          Oliver and Osoyoos. This enigmatic,           live in loose soil and evidently feed on
                                                      rare predator lives mostly on the       other invertebrates there. Look for these
         The south Okanagan occupies a tiny           ground and low in shrubs such as        flies on hot days in August.
         fraction of the area of the province         sage and antelope brush, where
                                                      its dusty brown colour makes it
                                                      hard to find. The males are usu-
                                                      ally fully winged, but females are
                                                      flightless – their wings are greatly     Robber Fly
                                                      reduced, less than one-third the        Megaphorus
                                                                                              willistoni (Cole)
                                                      length of the abdomen. In the late
                                                      summer and fall, females lay a          Only one specimen of
                                                      small, rectangular egg mass about       this small robber fly (Order
                                                      7 mm long on the stems of low           Diptera) has been recorded in Canada,
                                                      shrubs. The eggs overwinter and         just a few hundred metres from the In-
                                                      hatch about six or seven months         ternational Boundary in the southern
Similkameen Valley.                                                                              females seek out the bur-
These are squat little flies                                                                      rowing larvae of big
bristling with grey and yel-                                                                     scarab beetles. They para-
low hairs, which give them                                                                       lyse each grub and lay an
an uncanny resemblance                                                                           egg directly on it – and
to leaf-cutter bees as they                                                                      the wasp larva consumes
buzz from plant to plant,                                                                        the beetle grub where it
hovering here and there in                                                                       lies. The scarab beetles
search of prey. They live in                                                                     themselves are probably
grasslands and seem to                                                                           rare and have a restricted
prefer areas with many                                                                           distribution. Thus far,
flowers, since this is where                                                                      these wasps are known
their favourite prey, small                                                                      only from Chopaka in
bees and wasps, abound.                                    the lower Similkameen
                                     
Like all robber flies, they   . Robert Cannings photo                        Valley and the sandy
capture their prey in their                                                                      benchlands east and
bristly legs and kill it with                                                                    north of Osoyoos Lake,
toxic saliva injected through their short                                        where much of their habitat was
proboscis. The dissolved tissues are then                                        destroyed by fire in 1993.
sucked back up through the proboscis.
Eggs are laid in a case-like mass on a                                           What can we do?

dead plant stem; the larvae develop in                                                ne of the first priorities is to find out
the soil where they apparently prey on                                                more about our rare invertebrates –
other insect larvae.                                                                  where exactly are they, and what sort
                                           Viceroy                                    of habitats do they need? It is critic-
                                           Limenitis archippus (Cramer)               al to bring together information
                                           The orange and black Viceroy (Order        from specimens that have already
                                           Lepidoptera) is the famous mimic                              been collected and
                                           of the poisonous Monarch butter-      One of the              housed in muse-
                                           fly. Although the Monarch still
                                           persists in small numbers in the
                                                                                 first priorities ums across North
                                                                                                         America. This ba-
                                           Thompson and Okanagan valleys,        is to find out sic information is
                                           the Viceroy has disappeared
                                           completely from the province,
                                                                                 more about vital toof inverte-
                                                                                                                  our knowl-

Mormon Metalmark                           probably a victim of orchard pesti-   our rare                brate species’ dis-
Apodemia mormo (Felder and Felder)         cides. It would have been especially
This handsome butterfly (Order Lepi- susceptible to these chemicals
                                                                                 invertebrates. tribution and eco-
                                                                                                         logical needs. The
doptera) of western North America was since some of its favourite larval                                 Royal        British
formerly found at several sites in the re- food plants are domestic fruit trees. Columbia Museum and the Spencer
gion, but is now known only from one                                             Entomological Museum at the Univer-
population near Keremeos. Elsewhere Scoliid Wasp                                 sity of British Columbia have important
in Canada another subspecies is found Campsomeris pilipes                        collections of Okanagan insects. In con-
in extreme southern Saskatchewan. The (Saussure)                                  junction with museums, the Conserva-
adults, which fly in August, sip nectar These huge, grey and                         tion Data Centre in the Wildlife
from wild buckwheats. The nocturnal yellow wasps (Order                                Branch can keep track of this infor-
larvae eat the leaves and stems of the Hymenoptera) can                                mation in the same way it now
same plants, living in a silken nest be seen hov-                                     manages data on rare vertebrates
during the day.                            ering low                              and plants. At the same time, detailed,
                                           over sandy                               but focused inventories of species
                                           soil, where the                             and their habitats are urgently
       ’                                 
     .                                    ,       .
Steve Cannings photo                                                   David Shackleton photo

needed to increase our knowledge.                But even before all the information is          on public land. We can get involved in
   Education is vital, too. Invertebrate      in, we must act quickly to protect the             public processes to develop land use
conservation will not be supported if no      natural communities that still remain in           plans and regulations that preserve,
one has heard of the animals in ques-         these special valleys.                             rather than destroy, natural diversity.
tion. Invertebrates, despite their vast di-      What can we do as individuals? We               And we can maintain natural habitat
versity and ecological importance, have       can get involved with local naturalist or-         on our own property and encourage
not had the attention, either from re-        ganizations to learn more about the                governments to develop incentives for
searchers or managers, that other or-         natural world in our neighbourhood.                others to do the same.
ganisms such as mammals, fish, birds           We can encourage all levels of govern-
and trees have had.                           ment to protect natural communities

                                                                    
                                                                       , :
                                                                                Wildlife Branch
                                                                                BC Environment
                                                                   Ministry of Environment, Lands and Parks
                                                                              780 Blanshard Street
                                                                     Victoria, British Columbia V8V 1X4

                                                                                                                   BRITISH COLUMBIA
                                                                                                                   DATA CENTRE

                                                                             
                                                                            B.C. Conservation Data Centre

                                                  ---                                 
                                                                                                    
                                                  .                                   
                                                                                                    
                                                                                          ,  
                                                                                                    
                                                                                                    
                                                 Printed in British Columbia on recycled paper with vegetable base inks.
                                                 .. 

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