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The collection of maple sap for the production of maple syrup is a large commercial enterprise in Canada and the United States. In Canada, which produces 85% of the world’s supply, it has an annual value of over $168 million CAD. Over 38 million trees are tapped annually, 6.5% of which use traditional buckets for sap collection. These buckets attract significant numbers of insects. Despite this, there has been very little investigation of the scale of this phenomenon and the composition of insects that are attracted to this nutrient source. The present paper reports the results of a preliminary study conducted on Prince Edward Island, Canada. Twenty-eight species of Coleoptera, Lepidoptera, and Trichoptera were found in maple sap buckets, 19 of which are known to be attracted to saps and nectars. The physiological role of sap feeding is discussed with reference to moths of the tribe Xylenini, which are active throughout the winter, and are well documented as species that feed on sap flows. Additionally, 18 of the 28 species found in this study are newly recorded in Prince Edward Island.
Coleoptera, Nitidulidae, Lepidoptera, Xylenini, Trichoptera, Prince Edward Island, Canada, maple sap, maple syrup, biodiversity
The collection of maple sap for the production of maple sugar has a
long history in North America. Before the arrival of European settlers,
native people in northeastern North America collected maple sap,
pouring it into hollowed-out logs in which heated stones were placed to
evaporate the water and concentrate the syrup. In the 1880’s a
significant innovation was the introduction of the forerunner to the
contemporary flue pan evaporator (
Canada produces 85% of the world’s maple syrup; the United States the other 15%. Annual Canadian production in 2007 was 5.235 million gallons of syrup valued at over $168 million CAD. Québec accounts for 91.1% of domestic production followed by New Brunswick (4.5%), Ontario (3.9%), and Nova Scotia (0.5%). Small volumes are also produced in Prince Edward Island. In the United States, production in 2006 was 1.449 million gallons from producers in Vermont (32%), Maine (21%), New York (17%), Wisconsin (7%), Michigan (5%), Ohio (5%), Pennsylvania (5%), New Hampshire (4%), Massachusetts (3%), and Connecticut (0.7%) (Agriculture and Agri-Food Canada 2007).
In 2006 in Canada, 9, 731 maple sugar producers had an average
per-farm tap number of 3, 913 indicating that approximately 38, 077, 400
trees were being tapped. Two collection methods are used: the
traditional bucket system placed on trees, and plastic tube collection.
In Ontario 78% of collection is with plastic tubing and 22% is by
traditional buckets (
Despite the long history of maple syrup production, which has
evolved to become a significant industry in Canada and the northeastern
United States, and the very sizeable number of trees that are tapped
over a considerable portion of the continent, there has been remarkably
little attention paid to the insects that are attracted to maple sap
during extraction and collection. Sap is largely contained with the
plastic tubing collection method and except for local spots surrounding
the borehole, there is little opportunity for insects to avail
themselves of this resource. In traditional bucket collection the
opportunity for attracting insects to sap is considerably greater. Maple
sap typically consists of 97.5% water, 2.4% sugars (primarily sucrose
with small amounts of glucose), and 0.1% minerals (primarily potassium
and calcium, with smaller quantities of zinc and manganese, and trace
amounts of other minerals). There are also trace amounts of phenolic
compounds, primary amines, peptides, amino acids, and other organic
compounds. (
Many species of moths attracted to sugar solutions on trees,
indeed “sugaring” for moths is an important collection technique for
many species of nocturnal Lepidoptera. In a poetic essay entitled “Sugaring for Moths” in The Moth Book,
Amongst Coleoptera, members of Nitidulidae (sap beetles) are well known to be attracted to natural sap flows on a variety of trees.
There has been considerable interest in sap flows caused by Yellow-bellied Sapsuckers (Sphyrapicus varius Linnaeus) (Aves: Picidae) and the insects attracted to these. Studies such as
There are few references in entomological literature of insects specifically associated with the collection of maple sap.
On 4 April 2010 while at a maple sugar collection site in Woodville Mills, Prince Edward Island, (46°14.03333'N; 062°31.06667'W), insects in maple sap collection buckets (n=70) were surveyed. The forest stand (4.2 hectares) consists of primarily deciduous trees [sugar maple, red oak (Quercus rubra L.), yellow birch (Betula alleghaniensis Britt), linden (Tilia europea L), pin cherry (Prunus pensylvanica L.f.), and others) with occasional intermixed conifers [red spruce (Picea rubens Sarg, ), white spruce (Picea glauca (Moench) Voss), balsam fir (Abies balsamaea (L.) Mill)]. It is bounded along its lower margin by a small stream flowing from a marsh and beaver pond, along its upper margin by an apple orchard, and along both sides by agricultural fields. The spacing of sap collection buckets varied within this area. In some instance as many as three buckets were place on a single tree; in other instances buckets were as much as 10 meters apart, depending on the size and spacing of the sugar maple trees.
All buckets had covers on them to prevent extraneous debris from falling into the maple sap. Therefore insects present inside would almost certainly have had to actively enter the buckets, either from beneath the lids (where there was a gap at the front of the bucket) or in the small open area near the spigot. Thus, the suite of insects present would largely represent species actively attracted to maple sap, or seeking shelter in the buckets, as opposed to specimens that had accidentally fallen into the containers.
It was not possible to strictly quantify the results, since different buckets had been hanging with uncollected sap for varying periods (1–4 days) due to the impending conclusion of the sap collection season. Nevertheless general categories of abundance [scarce, fewer than 10 specimens; abundant, 10–30 specimens; very abundant, more than 30 specimens] were assigned for each of the species found.
Results and discussionThe results of this investigation are shown in Table 1. Diptera were also present but were not collected. Twenty-eight species were recorded including 18 Coleoptera, eight Lepidoptera, and two Trichoptera. After reviewing the biology of each species, it was possible to categorize them as species associated with sap and nectar, or accidental visitors.
Insects collected in maple sap, Woodville Mills, PEI, April 2010
Species | Abundance | PEI Status1 |
---|---|---|
COLEOPTERA | ||
Carabidae | ||
Dromius piceus Dejean | scarce | |
Coccinellidae | ||
Anatis mali (Say) | scarce | |
Corylophidae | ||
Orthoperus suturalis LeConte | scarce | |
Curculionidae | ||
Trypodendron retusum (LeConte) | abundant | new in PEI |
Xyloterinus politus (Say) | scarce | |
Xyloborinus alni (Niisima) † | scarce | new in PEI |
Dermestidae | ||
Anthrenus castanae Melsheimer | scarce | |
Histeridae | ||
Euspilotus assimilis (Paykull) | scarce | |
Lampyridae | ||
Ellychnia corrusca (Linnaeus) | very abundant | new in PEI |
Nitidulidae | ||
Cryptarcha ampla Erichson | scarce | new in PEI |
Glischrochilus fasciatus (Olivier) | abundant | |
Glischrochilus quadrisignatus (Say) | abundant | |
Glischrochilus sanguinolentus (Olivier) | scarce | |
Glischrochilus siepmanni Brown | scarce | |
Scirtidae | ||
Cyphon confusus Brown | scarce | new in PEI |
Cyphon variabilis (Thunberg) * | very abundant | new in PEI |
Staphylinidae | ||
Silusa californica Bernhauer | scarce | new in PEI |
Nudobius cephalus (Say) | scarce | new in PEI |
LEPIDOPTERA | ||
Noctuidae | ||
Crocigrapha normani (Grote) | scarce | new in PEI |
Eupsilia vinulenta (Grote) | abundant | new in PEI |
Eupsilia tristigmata (Grote) | abundant | new in PEI |
Lithophane innominata (J.B. Smith) | abundant | new in PEI |
Lithophane petulca Grote | scarce | new in PEI |
Lithophane pexata Grote | scarce | new in PEI |
Xylena cineritia (Grote) | scarce | new in PEI |
Tortricidae | ||
Acleris chalybeana (C.H. Fernald) | abundant | new in PEI |
TRICHOPTERA | ||
Limnephilidae | ||
Glyphopsyche irrorata (Fabricius) | scarce | new in PEI |
Limnephilus ornatus Banks | scarce | new in PEI |
†, adventive Palaearctic species; *, Holarctic species. 1 No entry indicates the species has previously been recorded in the province.
Due in large measure to the comparative dearth of entomological
research on Prince Edward Island, it is possible to report that 18 of
the 28 species found in this study are newly recorded in the province.
In the case of some species of Coleoptera (i.e., Ellychnia corrusca, Cyphon variabilis, Cyphon confusus, and Nudobius cephalus
(Say)) these new records represent broadly distributed species that
belong to groups that have not yet been surveyed on Prince Edward
Island. However the Prince Edward Island Curculionidae were surveyed by
Similarly, although some research has been conducted on the Noctuidae
of Prince Edward Island, the fauna remains poorly known and none of
the species recorded herein have previously been recorded from the
province (
Two species were hyper-abundant (more than 100 individuals each) in the sap buckets: Ellychnia corrusca and Cyphon variabilis.
Trypodendron retusum, Xyloterinus politus (Say), and Xyloborinus alni are all ambrosia beetles (Curculionidae: Scolytinae)
wherein adults excavate galleries beneath bark of unhealthy or dying
trees. These galleries are inoculated with symbiotic fungi carried in
mycangial pits on the heads of the beetle. Adults and larvae feed on the
resulting growth of fungal hyphae. Bark beetles are known to be
attracted to tree volatiles such as terpenes and oleoresins, so it may
be that these species are attracted to the maples via these chemicals
signals, and in seeking their source, the beetles secondarily fall
into the maple sap. Trypodendron retusum is associated with poplars (Populus grandidentata Michx. and Populus tremuloides Michx.) and is newly recorded on Prince Edward Island (
Cryptarcha ampla, Glischrochilus fasciatus (Olivier), Glischrochilus quadrisignatus (Say), Glischrochilus sanguinolentus (Olivier), and Glischrochilus siepmanni Brown are all sap beetles (Nitidulidae: Cryptarchinae) well known to be attracted to a variety of saps and liquids.
Although Anthrenus larvae such as Anthrenus castanae
Melsheimer, like other dermestids, feed on dried animal and plants
products, adults mate in the field and feed on nectar and pollen (
Dromius piceus Dejean is a nocturnal, arboreal predaceous ground beetle found in deciduous, coniferous and mixed forests (
Xylena cineritia (Grote), Lithophane innominata (J.B. Smith), Lithophane petulca Grote, Lithophane pexata Grote, Eupsilia vinulenta (Grote), and Eupsilia tristigmata (Grote) (Noctuiodae: Cuculliinae: Xylenini) were well represented in the maple sap buckets. They are all members of genera well known to be attracted to maple sap (
In addition to the noctuids discussed above, one tortricid, Acleris chalybeana
(C.H. Fernald), was abundant in maple sap buckets. This is a
widespread species whose hosts include apple, beech, birch, maple,
and oak (
The one noctuid collected which is not a member of this suite of moths, was a single specimen of Crocigrapha normani (Grote), a species whose hosts include apple, cherry, oak, and other deciduous trees (
Almost all adult Trichoptera are liquid feeders, consuming sap and floral nectar (
In summary, 28 species of Coleoptera, Lepidoptera, and Trichoptera were recovered from maple sap buckets at one site in Prince Edward Island. Nineteen of these are known to be attracted to sap and nectar. Two species, Cyphon variabilis and Cyphon confusus have not been documented as exhibiting an association with such substances, but the hyper abundance of the former species in collection vessels appears to indicate that an association does exist and reflects a hitherto undocumented feature of the biology of these species of marsh beetles. The remaining seven species (all represented by single individuals) are mostly found in deciduous forest stands, and their presence in maple sap containers would appear to be accidental.
Given that some 1.5 million are tapped in Canada employing traditional buckets, the number of insects collected annually through such activities must be considerable. This phenomenon may have both ecological repercussions, in terms of the impact of removing a sizeable number of adults from the population early in the reproductive season, as well as an economic impact in terms of the removal of drowned insects in the maple sap before processing. This preliminary study suggests further research on this phenomenon is needed to document not only a more complete taxon list, but also to aid the maple syrup industry in controlling unwanted insect contaminants through methods utilizing the biology of the species.
Thanks to Max Newby at Woodlands for his assistance. Also to Jan Klimaszewski and Robert Rabaglia for assistance with determinations. Sincere thanks to the Board of Governors of the Nova Scotia Museum for ongoing assistance.