Key to New England Lasius

AntWiki: The Ants --- Online

This key is modified from the 2012 book A Field Guide to the Ants of New England
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1

  • The maxillary palps are short and inconspicuous, and with three segments; these ants give off a very strong lemony/citronella odor when disturbed; the angle between the dorsal (top) and rear (declivity) faces of the propodeum is rounded (claviger group) . . . . . 2
  • Maxillary palps long and conspicuous, and with six segments; ants do not give off a lemony/citronella odor when disturbed; the angle between the dorsal face of the propodeum and its declivity is sharp . . . . . 7


2

return to couplet #1

  • The hairs on the gaster have feathery (plumose) tips (best viewed obliquely using a dissecting microscope at 50-100× magnification); currently unknown from New England Lasius plumopilosus
Lasius-plumopilosus-MCZ001H.jpg
Lasius-plumopilosus-MCZ001L.jpg
  • Hairs on gaster have straight tips without feathered ends . . . . . 3

3

return to couplet #2

  • The petiole, viewed in profile, is sharp and pointed; when viewed from the front, the petiole has a shallow-to-sharp depression in its center; cheeks, viewed from the side, with erect hairs sparse, or if dense, limited to the upper (posterior) 2/3 of the cheeks . . . . . 4
  • Petiole, viewed in profile, is rounded and blunt; cheeks, viewed from the side, with erect hairs distributed over the entire surface . . . . . 6

4

return to couplet #3

  • The hairs on the body are thin and wispy; the hairs on the cheeks are short . . . . . Lasius subglaber
Lasius subglaber casent0104878 head 1.jpg
Lasius subglaber casent0104878 profile 1.jpg
  • Hairs on the body are thick and coarse; the hairs on the cheeks are long . . . . . 5

5

return to couplet #4

  • Erect hairs are present on all surfaces of all segments of the gaster; hairs on the ventral surface of the head are long . . . . . Lasius claviger
Lasius claviger casent0103541 head 1.jpg
Lasius claviger casent0103541 profile 1.jpg
  • Erect hairs are present on the entire surface of the first segment of the gaster but are present only on the posterior edges of the second and third segments; few hairs on the ventral surface of the head . . . . . Lasius interjectus
Lasius interjectus casent0103545 head 1.jpg
Lasius interjectus casent0103545 profile 1.jpg

6

return to couplet #3

  • The ant is very hairy all over; there are many long hairs on the cheeks . . . . . Lasius latipes
Lasius latipes casent0005399 head 1.jpg
Lasius latipes casent0005399 profile 1.jpg
  • Hairs on the propodeum denser than elsewhere; hairs on the cheeks are short . . . . . Lasius murphyi
Lasius-murphyi-MCZ001H.jpg
Lasius-murphyi-MCZ001L.jpg

7

return to couplet #1

  • The ant has large eyes (eye length > 1/5th the width of the head); the color of the ant is golden-brown to dark-brown (niger group) . . . . . 8
  • Eyes smaller (eye length < 1/6th the width of the head); nests can be deep underground; the color is yellow-to-brown . . . . . 11

8

return to couplet #7

  • The basal tooth of the mandible (i.e., the tooth closest to head) is offset from, and smaller than, the others; there are 7 teeth on the mandible, but because the basal tooth is offset, it may appear that there are only 6; the anterior margin of the clypeus is broadly curved; erect hairs are present on the scape and tibia; color dark brown . . . . . Lasius pallitarsis
Lasius pallitarsis casent0005405 head 1.jpg
Lasius pallitarsis casent0005405 profile 1.jpg
  • Basal tooth of the mandible aligned with the rest of the teeth and normal in size; there are 7 teeth on the mandible and all are usually visible; the anterior margin of the clypeus may be broadly curved or sharply angular in the middle . . . . . 9

9

return to couplet #8

  • There are usually no erect hairs (if present, always < 10) on the antennal scape or tibia; color dark brown; forested habitats in New England . . . . . Lasius americanus (the North American species long considered to be Lasius alienus has been shown to be a separate species. L alienus is restricted to the Palearctic and L. americanus is the name for the North America species).
Lasius alienus casent0172724 head 1.jpg
Lasius alienus casent0172724 profile 1.jpg
  • There are many erect hairs on the antennal scape (usually) and on the tibia (always); color golden-brown; found in open habitats . . . . . 10

10

  • With the mandibles fully open and the head positioned in full-face view, the anterior margin of the clypeus is sharply angled; the basal 2 – 3 teeth on the mandible are irregularly spaced and the second tooth is usually much smaller than the 1st or 3rd tooth . . . . . Lasius neoniger
Lasius neoniger casent0005403 head 1.jpg
Lasius neoniger casent0005403 profile 1.jpg

10b. With the mandibles fully open and the head positioned in full-face view, the anterior margin of the clypeus is broadly curved; the basal 2 – 3 teeth on the mandible are regularly spaced and equal in size . . . . . L. cf. niger

11

return to couplet #7

  • Eyes much shorter than 1/6th the width of the head and with < 35 facets (flavus group) . . . . . 12
  • Eyes about 1/6th as long as the head is wide and always with > 35 facets; all species are temporary social parasites on other species of Lasius (umbratus group) . . . . . 13

12

return to couplet# 11

  • The terminal segment of the maxillary palp is usually shorter than, but never longer than, the next-to-last segment; color yellow to dark yellow-brown; usually in open habitats . . . . . Lasius flavus
Lasius flavus casent0173167 head 1.jpg
Lasius flavus casent0173167 profile 1.jpg
  • Terminal segment of the maxillary palp always longer than next-to-last segment; color pale-to-medium yellow; usually in forested habitats . . . . . Lasius nearcticus
Lasius nearcticus casent0104774 head 1.jpg
Lasius nearcticus casent0104774 profile 1.jpg

13

return to couplet #11

  • The second gastral segment is shiny and lacks appressed pubescence, but may have at most a few scattered erect hairs; color dark-yellow to medium-brown; occurs in bogs, fens, and moist woods . . . . . Lasius speculiventris
Lasius-speculiventris-MCZ001H.jpg
Lasius-speculiventris-MCZ001L.jpg
  • Second gastral segment dull, with both appressed pubescence and many erect hairs . . . . . 14

14

return to couplet #13

  • The longest hairs of the first gastral segment are short and stubble-like: < ½ the width of the hind tibia at its midpoint . . . . . 15
  • Longest hairs of the first gastral segment are long (> 2/3 the width of the hind tibia); found in moist, disturbed, and early successional habitats . . . . . 16

15

return to couplet #14

  • The petiole viewed from front (or rear) is concave on top; no erect hairs are present on the scape or tibia Lasius umbratus
Lasius umbratus casent0103993 head 1.jpg
Lasius umbratus casent0103993 profile 1.jpg

16

return to couplet #14

  • The hairs on the gaster are between 2/3rd and 4/5th the maximum width of the hind tibia; there are some erect hairs present on the tibia; petiole viewed from front or rear evenly convex at top; color is clear yellow . . . . . Lasius subumbratus
Lasius subumbratus casent0005408 head 1.jpg
Lasius subumbratus casent0005408 profile 1.jpg
  • Hairs on the gaster as long or longer than the maximum width of the hind tibia; no erect hairs present on the tibia; color is brownish-yellow; open habitats, especially bogs, fens, and sedge meadows . . . . . Lasius minutus
Lasius minutus casent0104880 head 1.jpg
Lasius minutus casent0104880 profile 1.jpg