Orlando Park.
Beetles Associated with the Mound-Building Ant, Formica ulkei Emery.
Psyche 42:216-231, 1935.

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Psyche
[December
BEETLES ASSOCIATED WITH THE MOUND-
BUILDING ANT, FORMICA ULKEI EMERY
Northwestern University
The mound-building ant, Formica ulkei Emery, has been reported as far west as South Dakota to Nova Scotia and New Brunswick (Wheeler, 1926; Holmquist, 1928). It is recorded from Wisconsin (Burrill and Smith, 1918) and Illinois, and is apparently abundant in northern Ohio1 where its range merges with that of the eastern mound-builder, Formica exsectoides.
In Illinois vikei is at present known only from the Chi- cago Area where it is well established in two localities (Palos Park and Palatine). In both places the numerous mounds, varying from young nests of less than a foot in diameter up to old hills more than four feet across, are found within the upland oak-ash-hickory forests, where they tend to follow the forest margins and clearings. These ant mounds present an infinite array of problems which remained uninvestigated until 1926. Since then, a literature upon these Illinois mounds has steadily accumu- lated, including the life history and behavior of the host ant (Holmquist, 1928a), hibernation (Holmquist, 1928b ; Dreyer, 19'32), distribution of the nests (Dreyer and T. Park, 1933), and the species of arthropods associated with the host ant (Park, 0., 1929; Park, T., 1929). Among the numerous arthropods associated with ants the myrmecocolous beetles are numerous, both in species and individuals. Many of these beetles are nest scavengers, I am indebted to Dr. C. H. Kennedy for personal communication upon the Ohio distribution of Formica ulkei and exsectoides. The latter species is reported from Iowa (Wickham, 1900) and Indiana (Blatch- ley, 1910) so that the actual distribution of these two closely allied ants can not be certainly known until a carefully planned survey can be made. Both ulkei and exsectoides are present in the Chicago Area, however; a small mound was investigated, and workers preserved, near Smith, Indiana on August 27, 1934. These ants I sent to Dr. M. R. Smith who determined them as Formica exsectoides. Piwht 42:216-231 t 1935). http:ffpsyche cnlclub ora/42/42-216 html



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19351 Beetles Associated with Ants 217
but the majority probably strike at the vitality of the society by feeding upon the host brood. The ant brood appears to be especially stimulating and may be infre- quently raided by species which may or may not live in the nest (Park, 1933a), attacked by tolerated nest preda- tors (Park, 1932b), or assiduously licked or devoured by highly specialized commensals and temporary ectoparasites (Park, 1932a, 1933b).
In the following table the beetles associated with Formica ulkei are listed with their seasonal range as far as known for the nests, and authority for the data. From the above table we find that ten families and fif- teen species of beetles have been reported from nests of F. ulkei, fourteen of which have been recorded from the Illinois mounds. In passing, mention should be made of the activity of these beetles during the last three weeks of May. Individuals were especially numerous during this period; two species, Atheta polita and Batrisodes globosus made repeated short flights of several inches on the eve- nings of May 12 and 13, and the syrphid flies of the genus Microdon3 pupated on the mornings of May 17 and 18. This
seasonal activity is in general agreement with the maximum appearance of species and individuals of Cole- optera in the Chicago area (Park, 1930), as well as that of isolated or specialized communities, e. g. beetle popu- lation of fungi (Park, 1931).
Formica ulkei and F. exsectoides are not only related tax- onomically, but ecologically they are very similar and it is interesting to observe identity of some, and ecological equiv- alence of other, myrmeeocoles from the mounds of these two species of hosts.
The following table (Table 11) lists
those species said to occur in the exsectoides nests as far as I have been able to ascertain from the literature. So far, no true guest (symphile) has been reported from either Formica ulkei or exsectoides nests. A comparison
of tables I and I1 shows that three species, Tachwa in- curvu, Megastilieus formicarius, and Hetserius brunnei- pennis, are common to both host ants, and the species of \
å´^Thes flies are at present being determined, and the data concern- ing their behavior in the nest, and pupation data are to be given later.




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Psyche [December
TABLE I
Coleoptera associated with Formica ulkei Family
Seasonal
Species record with host Citation
.... Carabidse.. Tachyura Holmquist, 1928 incurva.. ..... All year. ...... Park, O., 1929 (Say)
............. Clivima
bipustulata. ... May 7. ........ Present report (Fab.)
............... Amara April 11, Holmquist, 1928 polita LeC.. ... May 7. ...... Present report .............. Harpalus
..... ...
pleuriticus February 24. Holmquist, 1928 Kirby
Leptinidas.. .... Leptinus
..... .....
testaceus. October 6. Park, 0.. 1929
Mueller
.. Staphylinidse. Gastrolobium
...... bicolor.. May 7 to
(Graves) August 20. ... Present report
...
Atheta polita. March 1 to
............... Park, O., 1929
...
Melsh. October 6. Present report
Megastilicus Holmquist, 1928 ............... ...
formicarius.
March 1 to Park, O., 1929
Casey August 4. .... Present report
Pselaphidas. .... Batrisodes Holmquist, 1928 ..... ..... globosus.. All year.. Park, O., 1929 (LeC.1
9
Present report
Histeridas. ..... Hetasrius
........
brunneipennis. May 7. Present report
Rand.
.....
Cucujidas. Cathartus
advena.. ...... October 6.. .... Park, O., 1929 (Walt.)
.... Phalacridas. Stilbus
probatus. ..... September 13
Casey June 2.. ..... Present report
Elateridas. ..... Melanotus
communis.. ... August 6.. ..... Park, O., 1929 (GY~.)
Scarabseidse. ... Phyllophaga
horni.. ....... October 6.. .... Park, O., 1929 Smith
Chrysomelidse. . Coscinoptera
dominicana. ... Wisconsin
.....
(Fab.) record.. Burrill and
Smith, 1919
2Batrisodes globosus (Lee.) is probably the only species of this genus so far reported from these nests of Formica ulkei. In 1929 I reported that B. denticollis Casey was also present, but subsequent study and collection has proven that the latter were all females of the former species. Holmquist (1928) in addition reported the presence of a third species, B. spretus Lee. and, although I have not examined this latter material it is possible that this record also refers to females of globosus. Extensive and intensive collecting in these mounds since 1929 has never yielded either B. denticollis or B. spretus, although B. globosus is almost always to be had in numbers.



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19351 Beetles Associated with Ants 219
Coleoptera reported from nests of Formica exsectoides Family Species
Carabidse. . . . . . . . . . . . . . . . Bembidion quadrimaculatum .
( Linn.)
........................ Tachyura
incurva (Say) . . .
Staphylinidse.. . . . . . . . . . . Edaphus nitidus LeC. . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . Megastilicus f~~micarius
. . . . .
Casey
. . . . . . . . . . . . . . . . . . . . . . . . Nematolinus longicollis . . . . . .
( LeC.)
. . . . . . . . . . . . . . . . . . . . . . . . Diochus schaumi Kr. . . . . . . . . . . . , .
...................... Goniusa
obtusa (Led) . . .
Pselaphidse.. . . . . . . . . . . . . Batrisodes scabriceps . . . . . .
(LeC.1
. . . . . . . . . . . . . . . . . . . . . . . . Batnsodes f,ossicauda . . . . . .
Casey
................... Cedius
ziegleri LeC.
. . . .
Histeridae.. . . . . . . . . . . . . . Psiloscelis harrisi LeC. . . . . .
. . . . . . . . . . . . . . . . . . . . . . Hetserius brunneipennis . . .
Rand.
Anthicidse.. . . . . . . . . . . . . . Anthicus melancholicus . . .
Laf.
Monotomidsa.. . . . . . . . . . . . Montoma fulvipes Melsh. . .
Scarabseidse. . . . . . . . . . . . . , Euphoria inda (Linn.) . . . .
. . . . . . . . . . . . . . . . . . . . . . . . Cremastocheilus .canaliculatus . . . .
Kirby
. . . . . . . . . . . . . . . . . . . . . . . . Cremastocheilus castanese . . . . . . . .
Kirby
Citation
Schwarz, 1889
Schwarz, 1889, 1890
Ulke, 1890
Schwarz, 1889
Schwarz, 1889
Wickham, 1900
Blatchley, 1910
Wheeler, 1926
Schwarz, 1889
Schwarz, 1889
Schwarz, 1889
Leng, 1928
Wickham, 1900
Schwarz, 1889
Leng, 1928
Schwarz, 1889
Schwarz, 1889
Liebeck, 1891
Wickharn, 1900
Dury, 1903
Wickham, 1900
Wickham, 1900
Wheeler, 1908
Wheeler, 1908




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220 Psyche [December
Batrisodes are probably ecologically equivalent. Such identity and parallelism when investigated more fully should further our imperfect understanding of host-guest interrelations within the nest biocoenose. In such a populous community as a F. zdkei nest it is expected that many species stray into the mound, or are taken in by the ants. The cases of Harpalus pleuriticus, Amara polita and Cathartus advena may indicate such acci- dental circumstance, penetration for purposes of hiberna- tion, or passing the day within the nest in the case of a nocturnal form such as polita. Other species may pass a part of their life cycle in the mounds, either accidentally (Melanotus communis) , or habitually (Microdon larvae). The larvae and pupae of Phyllophaga horni and other species not yet determined are rather abundant in the nests. Their presence may or may not be significant, but since many other scarabaeids are myrmecocolous, exclusive of the Cremastocheilini, (Riley, 1882 ; Smith, 1886 ; Schwarz, 1889; Wickham, 1892, 1896; Wheeler, 1908, 1926; Donis- thorpe, 1927) more investigation is needed in the case of the May-beetles.
The presence of the chrysomelid larvag of Coscinoptera dominicana in the Wisconsin ulkei mounds (Riley, 1882?; Burrill and Smith, 1919) is interesting, and suggests fur- ther study since the genus in North America, and in Eng- land and Europe related genera, are known to be myrmeco- colous in the larval and pupal stages (Riley, 1882 ; Schwarz, 1896 ; Wickham, 1898 ; Wheeler, 1926 ; Donisthorpe, 1902, 1927).
The single record for Clivinia bipustulata was probably accidental, and the beetle was undoubtedly stimulated by the darkness and moisture of the nest. It is a geocole by habit, burrowing in moist earth and mud margins of streams or marshes, and has been found to be nocturnal (Park and Keller, 1932). When taken, the beetle was a foot beneath the dome of the nest, in wet clay soil with a tem- perature of 16 C.O In a laboratory nest it buried during the day and was not found by the host ants. It was attacked and readily put to flight by such nest predators as Megas- tilicus f ormicarius.




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19351 Beetles Associated with Ants 221
Three of the small phalacrid beetle, Stilbus probatus,* were taken on September 13, 1932, from one part of a deep ulkei gallery, and six more from another nest at a depth of four feet on June 2, 1934. Their presence with ulkei was the only datum obtained, however, the records are of interest.
The small Atheta polita, belonging to a tribe of staphy- linids which includes many habitual myrmecocoles, is an all year resident of the ulkei nest. However, little is known concerning it. It is capable of making short evening flights, and in artificial nests easily evades the ants. Its food and ecological position within the nest society are unknown. Although it occurs elsewhere in some abundance, its con- tinual presence with ulkei can hardly be accidental. The exact status of another staphylinid, Gastrolobium bicolor, is also uncertain. It has been taken twice in the nests. A male and female were obtained on May 7, and a third beetle on August 20, 1932. These records are prob- ably accidental since the species is widely distributed over the Chicago Area, where it inhabits moist forest floors and stream margins beneath logs and stones. In the laboratory the beetles avoided the host ants, running away with up- lifted abdomens. On the night of May 18 one of the beetles attacked and dismembered and devoured three Batrisodes globose. Since the latter fills a constant niche in the ulkei society we see the possibilities for disturbing the equilib- rium of the biocoenose arising from even accidental pene- tration by a non-myrmecocolous predator. The role of Leptinws testacei^s5 is poorly understood, chiefly due to its presence in such a variety of habitats. It is found within the nests of small forest mammals, bird nests, certain of the social wasps, bees and ants and in isolated log mold, not harboring mammals. Such a list provokes inquiry as to the natural niche of the species, especially in view of the probable eetoparasitism of related 4The first lot were collected by the writer, and the second yroup by Mr. Strohecker. Both lots were independently determined by the '
writer, and by Mr. Emil LiLjeblad of the Field Museum. sin 1929 the following data were unfortunately omitted. Donis- thorpe (1909) records three- collecting's of Leptinus testaceus with Lasius fuliginosus but states that it is usually taken in nests of bees, birds, moles and small rodents.




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222 Psyche [Decelmber
leptinids, and has been discussed elsewhere (Park, 1929). These delicate animals, eyeless, extremely flattened, and of pale yellow color were apparently unmolested by the ulkei workers, but were attacked and devoured by nest preda- tors mentioned later. The food of this species remains uncertain, but as far as its presence with ulkei is con- cerned, it appears to be a tolerated form, one of the loricate synoeketes.
FIG. 1.
Diagram of some of the food interrelations among the myrme- cocoles of Formica ulkei Emery. The inner circle encloses the host species and its food supply; the intermediate circle contains those species where a definite association is known to exist with the host; the outer circle is reserved for either accidentals or those forms where the relationship is still obscure. The arrows point to the food and away from the feeder. The broken line indicates regurgitation of food by the host workers.



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19351 Beetles Associated with Ants 223
The small predaceous carabid, Tachyura incurva, on the other hand, is a year round occupant of the ulkei mounds, and is the most consistently abundant myrmecocole in the nest and trophoporic field. Schwarz (1889) thought the species an accidental visitor of ant nests, but later, with accumulation of data, reversed his opinion (1890) . In the laboratory nests the food of inma is highly diversified.
The beetles feed upon dead or disabled individ- uals of their own apeeies, dead and disabled host ants, the host brood, and dead insects brought into the nest by the worker ants. In addition, the ulkeicoles are also attacked where the species offers little resistance (Leptinus testaceus, Atheta pol&), or are eaten when injured (Microdon larvae, queens of the lestobiotic guest ant, Solenopsis molests.) . Finally, incurva fed upon the sugar water and honey placed in the artificial nests.
The nest conditions are apparently very favorable for the species and its general behavior has been discussed elsewhere (Park, 1929). It appears to be a tolerated form, or at least very successful in avoiding persecution by the host ants.
Its catholic feeding habits fit it for the general role of nest scavenger, although it may be strictly predaceous upon occasion,
We now turn to an habitual myrmecocole, the actively persecuted staphylinid, Megastilieus fo~micarius. It is com- mon in the nests of F. exseetoides (Schwarz, 1889 ; Hatch- ley, 1910 ; Wickham, 19001, and Wheeler (1926) discusses the relation of this latter host to the beetle upon (1) the red and black coloration and ant-like appearance of the species, (2) its defensive mechanism, which is similar to that of the related staphylinid Myrmedonia, consisting of emitting a volatile whitish fluid from the raised tip of the flexible abdomen, and (3) that the ants kill the beetle with- in a few hours when in laboratory nests, but are eluded easily by the beetles in nature. He found formicarius too feeble to kill living- exseetoides workers. Formicarim has been taken repeatedly from the ulkei nests and studied in the laboratory. The above summary of its relations with exsectoides has been found to hold in general for idkei. However, in the artificial nests of ulkei, formicanus is an agile and wary species. The ants attack



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224 Psyche [De'cember
the beetles whenever the opportunity is presented, but with very indifferent success. When attacked the beetles usually wheel to present the posterior end to the ant and raise the apex of the abdomen. At times the beetle merely crouches, with the head lowered and antennae pressed back and in to the body, while the abdomen is raised and its apex directed forwards over the sloping elytra. Both maneu- vers serve the same purpose, the ant recoiling and behav- ing as though temporarily stunned. Meanwhile, the beetle escapes.
Infrequently, upon meeting an ant the formicarius would not raise the abdomen but would dodge away and attempt flight, either by running or by crouching and then crawling away between the ant's legs as the ant attempted to bite the beetle. If this retreat was blocked then the abdominal defense was successfully employed.
The worker ulkei almost always attacked these beetles at the slender neck or peduncle between the head and pronoturn. Once such a hold was obtained the outcome was more doubtful. I have witnessed such combats where the ant had seized a beetle by the neck and the two strug- gled back and forth. One of these encounters lasted twenty- five minutes continuously, with the beetle thrusting the apex of its abdomen at the ant's head. At the end of this time the ant still held the beetle's neck between her man- dibles, but appeared inert otherwise. The ant's jaws were pried apart and the formicarius ran off, unharmed, but the ant proved to be dead. The same beetle was then examined but the integuments were not even scratched. Of course, the ant may have been an enfeebled individual but we think that it was killed by the beetle's abdominal secre- tion. The protection of formicarius from ulkei, then, lies in (1) a hard exoskeleton, (2) agility, and (3) a defen- sive abdominal secretion which, under certain conditions at least, may be lethal.
At times a formicarius would be killed, when placed in a small watch glass with five or six workers. This usually happened during the night, and although the beetle would be dismembered, it was not eaten.
So far Megasfilicus formicarius has not been observed to feed on dead host ants, although this is to be expected.



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19351 Beetles Associated with Ants 225
It does feed upon injured Microdon larvae, chewing the flesh of wounds and licking the exuding body fluids. It has also been observed to attack and put to flight the larger staphylinid, Gastrolobium bicolor. Formicark drinks from small pools of water in the artificial nests. In
drinking, the head is lowered and the fore-legs spread apart; the water is pushed into the mouth by the maxillae and la- bium, while the mandibles are held widely agape and partly immersed in the liquid.
After feeding, f ormicarius cleans itself elaborately. The
vertex is rubbed by the prothoracic tarsi, usually both legs scraping together. The antennae are cleaned by pushing them between the slightly gaping mandibles from above. The antennae are then pulled back and forth, usually one at a time, in part by their own activity, but also by the fore-legs which push them upwards. After the antennae