Pitfall traps were installed in alfalfa fields to monitor the seasonality and abundance of immature ground beetles. Head capsule widths were determined by instar for Evarthrus sodalis, Harpalus pennsylvanicus, Chlaenius tricolor, Scarites subterraneus, Amara cupreolata, and A. impuncticollis. Seasonality of larval and adult catches indicated that E. sodalis, H. pennsylvanicus and A. impuncticollis overwinter in a larval diapause while A. cupreolata and S. subterraneus overwinter in the adult stage

Barney, R J

Pass, B. C

English

ValpoScholar

The Great Lakes Entomologist 
Volume 19 
Number 3 - Fall 1986 Number 3 - Fall 1986 Article 2 
October 1986 
Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: 
Carabidae) in Kentucky Alfalfa Fields 
R J. Barney 
Kentucky State University 
B. C. Pass 
University of Kentucky 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Barney, R J. and Pass, B. C. 1986. "Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: 
Carabidae) in Kentucky Alfalfa Fields," The Great Lakes Entomologist, vol 19 (3) 
Available at: https://scholar.valpo.edu/tgle/vol19/iss3/2 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
1986 THE GREAT LAKES ENTOMOLOGIST 147 
PITFAUJ TRAP COLLECTIONS OF GROUND BEETLE LARVAE 
(COLEOPTERA: CARABIDAE) IN KENTUCKY ALFALFA FIELDS 1 
R. J. Barney2 and B. C. Pass3 
ABSTRACT 
Pitfall traps were installed in alfalfa fields to monitor the seasonality and abundance of 
immature ground beetles. Head capsule widths were determined by instar for Evarthrus 
sodalis, Harpalus penn.l'ylvanicus, Chlaenius tricolor, Scarites .I'llbterraneus, Amara 
cupreolata, and A. impuncticollis. Seasonality of larval and adult catches indicated that E. 
sodalis, H. pellnsyivalliclls and A. impllllcticollis overwinter in a larval diapause while A. 
cupreolata and S. subterraneus overwinter in the adult stage. 
The ground beetle community has been investigated for many agroecosystems: corn 
(Dritschilo and Wanner 1980), soybeans (Bechinski and Pedigo 1981, House and All 
1981), apple orchards (Holliday and Hagley 1978), and alfalfa (Barney et al. 1979, Los 
and Allen 1983). Although our understanding of the importance of the adult carabid 
community in these crops ha  increased, research on immatures has been restricted 
because larvae, unlike adults, rarely venture far from their burrows in the soil. When 
larvae have been collected with adults, the best method to associate these morphologically 
different life stages s through the rearing of larvae to the adult stage. This is difficult 
because many species are cannibalistic. Difficulty in collecting, handling, and identifying 
immatures suggests that many specimens remain untrapped, overlooked, or unidentified. 
There has been a lack of adequate identification aids since van Emden's (1942) key to 165 
genera. A few updated, carabid-Iarvae identification aids have been published (Dogger 
and Olson 1966, Kirk 1972a, Thompson and Allen 1974, Goulet 1979, Thompson 1979), 
and Goulet (1976) and Thompson (1979) described methods for obtaining and rearing 
larvae. 
Our study was done to determine the seasonality and abundance of the most common 
in 
alfalfa fields and to determine limits for head capsule width 
by instar. 
:-'1ATERIALS AND METHODS 
Pitfall traps were installed in two alfalfa fields in the spring of 1983 at the Spindletop 
Research Farm, Kentucky Agricultural Experiment Station, Lexington, to monitor ground 
beetle activity. A trap consisted of a plastic cup (7 em diam) containing a dilute ethylene 
preservati\'e solution within a larger plastic cup ( 10 em diam) positioned at ground 
I:>.Iorrill 19751. 
Each trap was equipped with a plastic rain cover (23.5 em diam) 
suspended 
10 em abo\'e the soil surface by wooden stakes. The 64 traps were checked 
weekly from 25 :\pril to:; ~oyember 1983. 1.+ ~larch to 6 November 1984, and 13 May 
:The ID\'estigation reported in this paper (No. 85-7-234) is in connection with a project of the 
Kenruc\,:y Agriculrural Experiment Station and is published with approval of the Director. 
"Community Research Service. Kentuckv State University, Frankfort, KY 4060L 
:~partmelit 
of Entomology. University 'of Kentucky, Lexington, KY 40546. 
1
Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Car
Published by ValpoScholar, 1986
148 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 
to 27 
September 1985. A representative sample of larvae from the 1983 collections was 
sent to Dr. Yves Bousquet. Biosystematics Research Institute, Agriculture Canada, for 
identification 
so that those individuals could be sed to compile a more complete 
accounting of the 1984 and 1985 larval catches. 
Adults were collected from dry pitfall traps placed in an alfalfa border strip surrounding 
one field and held in 27.0 by 19.0 by 9.°cm plastic food crispers containing soil. Crispers 
were kept in a chamber at 21 ± 3°C under a 15:9 h (LD) photoperiod. Several species 
mated in the crispers and eggs recovered from the soil were individually placed in 
4.0-diam by 6.0-cm-high plastic vials containing 3. °cm of soil. Vials were checked every 
2-3 
days for exuviae and the soil changed when needed. Larvae were offered pieces of 
caterpillar and foxtail seeds. Head capsule widths for each stadium were measured with an 
ocular micrometer. 
RESULTS AND DISCUSSION 
Over 12,000 adults representing 40 species were trapped, indicating a large and diverse 
population 
of carabids. However. fewer than 300 carabid larvae were recovered from the 
traps. Genera such as Evarthrus and Harpalus that were well represented as adults were 
less abundant in the larval collections. Larvae f these genera may not be very mobile or 
active on the soil surface and therefore not subject to capture by pitfall traps. 
Head capsule width measurements for each genus were grouped into three size 
categories, one for each instar. These data were then analyzed to determine conformity to 
Dyar's rule (Dyar 1890) that growth of successive instars is represented by a geometric 
progression, assuming that no head capsule expansion occurs during each stadium. Dyar's 
ratio is calculated for a species by dividing the mean head capsule width of each instar by 
that of the successive instar. In this study we found a mean ratio of 0.72 with a range of 
0.68-D.74 (Table I), which compares favorably to those of Dyar. 
Larvae were identified to genus. Those of Evarthrus were considered to be E. soda lis 
LeConte because of the abundance of adults captured during the study. While this was the 
most abundant species in the adult samples, very few larvae were collected. Although 
only one third instar was caught, its width was almost identical to van Emden's (1942) 
reported mean of 2.27 mm (n 2). We believe this species overwinters as second and 
third ins tars because adults and first instars were found in the summer, second instars in 
the fall, and the lone third instar in the spring. 
Mating of E. sodalis was observed in the crispers but only four eggs were recovered. 
First instars were offered pieces of caterpillar and seeds but never fed. Mandibles of the 
larvae are sickle-like, indicating that the larvae are probably fluid-feeders and predaceous. 
The majority of Harpalus larvae were probably H. pennsylvanicus ( pensylvanicus) 
De Geer, on the basis of the overwhelming abundance of this species in the adult catches. 
Chu (1945) reported a head capsule width of 3.2 mm, which must have been a third instar. 
Apparently this species also overwinters in the larval stage because only first instars were 
captured in the fall. Kirk (1973) believed that this species overwintered in a larval 
diapause in South Dakota. 
H. pennsylvanicus readily oviposited n the crispers during October and eggs were 
found individually throughout the soil. This same observation was made by Kirk (1973) 
and Tomlin (1975). A total of 56 eggs was isolated in vials. Mean egg size before 
eclosion was, 1.73 by 2.56 mrn, a size increase of 18% over the size at oviposition (1.44 
by 2.20 mm). Tomlin (1975) measured the eggs to be 1.6 by 2.5 mm at oviposition. 
Larvae were provided foxtail seeds which were often later found in tunnels the larvae 
constructed. Kirk (I 972b) also found foxtail seeds in tunnels, but none showed feeding 
damage. Head capsule widths of the surviving larvae were recorded and added to the 
field-collected information in Table I. 
Although the larvae of Am ra were not separated to species by Dr. Bousquet, we 
believe the larvae ofAm r  can be divided into two species based on the field from which 
2
The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 2
https://scholar.valpo.edu/tgle/vol19/iss3/2
1986 THE GREAT LAKES ENTOMOLOGIST 149 
Table I. Head-capsule width measurements, limits, and ratios of successive instars for selected 
earabid larvae found in pitfall traps in alfalfa, Lexington, KY. 
Species Instar N x ± SE (mm) Limits (mm) Ratio 
.~mara 
cllpreolata 
1st 
2nd 
3rd 
32 
36 
8 
0.53 
± 0.01 
0.75 ± 0.01 
0.95 ± 0.02 
0.34-0.56 
0.64-0.83 
0.90-1.05 
0.70 
0.79 
Emrthrusif 
sodalis 
1st 
2nd 
3rd 
9 
7 
I 
1.07 ± 0.04 
1.63 ± 0.Q3 
2.26 ± -
0.90-1.36 
1.51-1.70 0.66 
0.72 
Harpalui' 
pennsylmnicu5 
1st 
2nd 
3rd 
75 
15 
12 
1.73 ± 0.01 
2.34 ± 0.04 
2.84 ± 0.05 
1.36-1.92 
2.11-2.56 
2.64-3.17 
0.74 
0.82 Chlaenills 
tricolor 
1st 
2nd 
3rd 
31 
8 
8 
0.69 
± 0.02 
1.00 ± 0.03 
1.38 ± 0.Q3 
0.41-0.87 
0.90-1.13 
1.28-1.54 
0.69 
0.72 
Scarites 
5ubterraneus 
1st 
2nd 
3rd 
37 
20 
12 
1.55 
± 0.04 
2 39 ± 0.04 
3.17 ± 0.05 
L 17-1.88 
2.03-2.64 
2.94-3.43 
0.65 
0.75 
Amara 
impuncticollis 3rd 22 1.21 ± 0.01 1.13-1.32 
"Contains four head capsule measurements of 1st instars from laboratory-reared in addition to 
field-collected specimens. 
bContains 42 head capsule measurements of 1 st ins tars from laboratory-reared in addition to 
field-collected specimens. 
were trapped and the species of adults found there. All the larvae designated as A. 
implmcticollis Say were collected during June in a field where only adults of that species 
were represented in pitfall catches. Larvae of Amara cupreolata Putzeys were collected 
from a different field that had very few adult Amara belonging to other species. 
Larvae of A. cupreolata were present from late May through July. This species 
overn'inters as adults because adults were active very early in the spring. However, A. 
impuncticollis adults were not active until July, which was after the collection of larvae 
in 
June. This species probably overwinters in an immature stage. The molar-like shape 
of 
the mandibles suggests that larvae of Amara are omnivorous, as are the adults. 
The Chlaenius larvae were probably C. tricolor Dejean. These larvae have sickle-like 
mandibles adapted for piercing soft-bodied prey, as do other known members of this 
genus (Kirk 1972a). Larochelle (1974) surveyed the Chlaenius literature and believed C. 
tricolor 
adults to be omnivorous. These larvae must be very active foragers on the soil 
surface because large numbers 
of larvae were trapped in comparison to numbers of adults. 
First instars were active in June and July, second instars in July through September, and 
third instars in August and September. 
Some confusion exists as to the Scarites larvae. Blatchley (1910) recognized two North 
.-\merican species, S. subterraneus Fabricius and S. quadriceps Chaudoir, that he 
separated solely on the basis of size. Lindroth (1961) considered S. quadriceps to be a 
subspecies of S. subterraneus and we have followed his interpretation. Emden (1942) 
reported the mean second instar head capsule width of S. quadriceps as 2.39 mm; that 
corresponds exactly to our measurement (Table 1). First instars were found in June and 
July. but second instars were active from June through September. Most third instars were 
caught in August. 
3
Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Car
Published by ValpoScholar, 1986
150 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 
The seasonality, abundance, and head capsule widths of the most abundant carabid 
larvae in Kentucky alfalfa presented here should aid future researchers in characterizing 
immature carabids found in many agroecosystems in the eastern United States. Additional 
studies are needed to characterize the abundance, seasonality, and feeding behavior of 
carabid larvae because these immatures remain a relatively unknown entity in most 
agroecosystems. 
ACKNOWLEDGMENTS 
Thanks are cxtended to Dr. Yves Bousquet, Biosystematics Research Institute, 
Agriculture Canada, for his identification of larval Carabidae. 
LITERATURE CITED 
Barney, R. J., S. J. Roberts, R. D. Pausch, and E. J. Armbrust. 1979. Insect predators 
of 
the alfalfa weevil and clover root curculio (Coleoptera: Curculionidae) during fall 
field reentry. Great Lakes Entomol. 12:153--155. 
Bechinski, E. 
J., and L. P. Pedigo. 1981. Ecology of predaceous arthropods in Iowa 
soybean agroecosystems. Environ. Entomol. 10:771-778. 
Blatchley, W. S. 1910. An illustrated and descriptive catalogue f the Coleoptera or 
beetles (exclusive of the Rhynchophora) known to occur in Indiana. Nature, Indianap­
olis. 
Chu, H. 1945. The larvae of the Harpalinae unisetosae (Coleoptera, Carabidae). Entomol. 
Amer. 25:1-71. 
Dogger, J. R., and C. A. Olson. 1966. Larval characteristics of some North Dakota 
carabids (Coleoptera: Carabidae). Coleopt. BulL 20:91-96. 
Dritschilo, W .. and D. Wanner. 1980. Ground beetle abundance in organic and 
conventional com fields. Environ. Entomo!. 9:629-631. 
Dyar, H. G. 1890. The number of molts of lepidopterous larvae. Psyche 5:420-422. 
Emden, F. I. van. 1942. A key to the genera of larval Carabidae (Col.). Trans. Royal 
Entomo!. Soc. London 92:1-100. 
Goulet, H. 1976. A method for rearing ground beetles (Coleoptera: Carabidae). Coleopt. 
Bull. 30:33-36. 
__
. 1979. Contributions 
of characters of larvae to systematics of Carabidae. pp. 
205-208 in T. L. Erwin, G. E. Ball, and D. R. Whitehead (eds.). Carabid beetles: 
Their evolution, natural history, and classification. Junk Publ., The Hague. 
Holliday, N. J., and E. A. C. Hagley. 1978. Occurrence and activity of ground beetles 
(Coleoptera: Carabidae) in a pest management apple orchard. Canadian Entomol. 
110:113-119. 
House, G. 1., and J. N. All. 1981. Carabid beetles in soybean agroecosystems. Environ. 
Entomol. 10:194--196. 
Kirk, V. M. 1972a. Identification of ground beetle larvae found in cropland in South 
Dakota. Ann. Entomol. Soc. Amer. 65:1349-1356. 
__
. 1972b. Seed-catching 
by larvae of two ground beetles, Harpalus pensylvanicus 
and H. erraticus. Ann. Entomol. Soc. Amer. 65:1426-1428. 
__
. 1973. Biology 
of a ground beetle. Harpalus pensylvanicus. Ann. Entomo!. Soc. 
Amer. 65:513-518. 
Larochelle, A. 1974. A world list of prey of Chlaenius (Coleoptera; Carabidae). Great 
Lakes Entomo!' 7:137-142. 
Lindroth, C. H. 1961. The ground-beetles (Carabidae, exc!. Cicindelinae) of Canada and 
Alaska. Part 2. Opusc. Entomol. (Supp!.) 20:1-200. 
Los, L. M., and W. A. Allen. 1983. Abundance and diversity of adult carabidae in 
insecticide-treated an  untreated alfalfa fields. Environ. Entomol. 12: 1068-1072. 
Morrill, W. L. 1975. Plastic pitfall trap. Environ. Entomol. 4:596. 
4
The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 2
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1986 THE GREAT LAKES ENTOMOLOGIST 151 
Thompson, R. G. 1979. Larvae of North American Carabidae with a key to the tribes. pp. 
209-291 in T. L. Erwin, G. E. Ball, and D. R. Whitehead (eds.). Carabid beetles: 
Their evolution, natural history, and classification. Junk Publ., The Hague. 
Thompson, R. G., and R. T. Allen. 1974. Descriptions of larval Carabidae. I. Coleopt. 
Bull. 28:185-201. 
Tomlin. A. D. 1975. Notes on the biology and rearing of two species of ground beetles, 
Pterostichus melanarius and Harpalus pensylvanicus (Coleoptera: Carabidae). Cana­
dian Entomol. 107:67-74. 
5
Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Car
Published by ValpoScholar, 1986


Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Carabidae) in Kentucky Alfalfa Fields

Valparaiso University

The Great Lakes Entomologist Volume 19 Number 3 - Fall 1986 Number 3 - Fall 1986 Article 2 October 1986 Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Carabidae) in Kentucky Alfalfa Fields R J. Barney Kentucky State University B. C. Pass University of Kentucky Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Barney, R J. and Pass, B. C. 1986. "Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Carabidae) in Kentucky Alfalfa Fields," The Great Lakes Entomologist, vol 19 (3) Available at: https://scholar.valpo.edu/tgle/vol19/iss3/2 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1986 THE GREAT LAKES ENTOMOLOGIST 147 PITFAUJ TRAP COLLECTIONS OF GROUND BEETLE LARVAE (COLEOPTERA: CARABIDAE) IN KENTUCKY ALFALFA FIELDS 1 R. J. Barney2 and B. C. Pass3 ABSTRACT Pitfall traps were installed in alfalfa fields to monitor the seasonality and abundance of immature ground beetles. Head capsule widths were determined by instar for Evarthrus sodalis, Harpalus penn.l'ylvanicus, Chlaenius tricolor, Scarites .I'llbterraneus, Amara cupreolata, and A. impuncticollis. Seasonality of larval and adult catches indicated that E. sodalis, H. pellnsyivalliclls and A. impllllcticollis overwinter in a larval diapause while A. cupreolata and S. subterraneus overwinter in the adult stage. The ground beetle community has been investigated for many agroecosystems: corn (Dritschilo and Wanner 1980), soybeans (Bechinski and Pedigo 1981, House and All 1981), apple orchards (Holliday and Hagley 1978), and alfalfa (Barney et al. 1979, Los and Allen 1983). Although our understanding of the importance of the adult carabid community in these crops ha  increased, research on immatures has been restricted because larvae, unlike adults, rarely venture far from their burrows in the soil. When larvae have been collected with adults, the best method to associate these morphologically different life stages s through the rearing of larvae to the adult stage. This is difficult because many species are cannibalistic. Difficulty in collecting, handling, and identifying immatures suggests that many specimens remain untrapped, overlooked, or unidentified. There has been a lack of adequate identification aids since van Emden's (1942) key to 165 genera. A few updated, carabid-Iarvae identification aids have been published (Dogger and Olson 1966, Kirk 1972a, Thompson and Allen 1974, Goulet 1979, Thompson 1979), and Goulet (1976) and Thompson (1979) described methods for obtaining and rearing larvae. Our study was done to determine the seasonality and abundance of the most common in alfalfa fields and to determine limits for head capsule width by instar. :-'1ATERIALS AND METHODS Pitfall traps were installed in two alfalfa fields in the spring of 1983 at the Spindletop Research Farm, Kentucky Agricultural Experiment Station, Lexington, to monitor ground beetle activity. A trap consisted of a plastic cup (7 em diam) containing a dilute ethylene preservati\'e solution within a larger plastic cup ( 10 em diam) positioned at ground I:>.Iorrill 19751. Each trap was equipped with a plastic rain cover (23.5 em diam) suspended 10 em abo\'e the soil surface by wooden stakes. The 64 traps were checked weekly from 25 :\pril to:; ~oyember 1983. 1.+ ~larch to 6 November 1984, and 13 May :The ID\'estigation reported in this paper (No. 85-7-234) is in connection with a project of the Kenruc\,:y Agriculrural Experiment Station and is published with approval of the Director. "Community Research Service. Kentuckv State University, Frankfort, KY 4060L :~partmelit of Entomology. University 'of Kentucky, Lexington, KY 40546. 1Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: CarPublished by ValpoScholar, 1986148 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 to 27 September 1985. A representative sample of larvae from the 1983 collections was sent to Dr. Yves Bousquet. Biosystematics Research Institute, Agriculture Canada, for identification so that those individuals could be sed to compile a more complete accounting of the 1984 and 1985 larval catches. Adults were collected from dry pitfall traps placed in an alfalfa border strip surrounding one field and held in 27.0 by 19.0 by 9.°cm plastic food crispers containing soil. Crispers were kept in a chamber at 21 ± 3°C under a 15:9 h (LD) photoperiod. Several species mated in the crispers and eggs recovered from the soil were individually placed in 4.0-diam by 6.0-cm-high plastic vials containing 3. °cm of soil. Vials were checked every 2-3 days for exuviae and the soil changed when needed. Larvae were offered pieces of caterpillar and foxtail seeds. Head capsule widths for each stadium were measured with an ocular micrometer. RESULTS AND DISCUSSION Over 12,000 adults representing 40 species were trapped, indicating a large and diverse population of carabids. However. fewer than 300 carabid larvae were recovered from the traps. Genera such as Evarthrus and Harpalus that were well represented as adults were less abundant in the larval collections. Larvae f these genera may not be very mobile or active on the soil surface and therefore not subject to capture by pitfall traps. Head capsule width measurements for each genus were grouped into three size categories, one for each instar. These data were then analyzed to determine conformity to Dyar's rule (Dyar 1890) that growth of successive instars is represented by a geometric progression, assuming that no head capsule expansion occurs during each stadium. Dyar's ratio is calculated for a species by dividing the mean head capsule width of each instar by that of the successive instar. In this study we found a mean ratio of 0.72 with a range of 0.68-D.74 (Table I), which compares favorably to those of Dyar. Larvae were identified to genus. Those of Evarthrus were considered to be E. soda lis LeConte because of the abundance of adults captured during the study. While this was the most abundant species in the adult samples, very few larvae were collected. Although only one third instar was caught, its width was almost identical to van Emden's (1942) reported mean of 2.27 mm (n 2). We believe this species overwinters as second and third ins tars because adults and first instars were found in the summer, second instars in the fall, and the lone third instar in the spring. Mating of E. sodalis was observed in the crispers but only four eggs were recovered. First instars were offered pieces of caterpillar and seeds but never fed. Mandibles of the larvae are sickle-like, indicating that the larvae are probably fluid-feeders and predaceous. The majority of Harpalus larvae were probably H. pennsylvanicus ( pensylvanicus) De Geer, on the basis of the overwhelming abundance of this species in the adult catches. Chu (1945) reported a head capsule width of 3.2 mm, which must have been a third instar. Apparently this species also overwinters in the larval stage because only first instars were captured in the fall. Kirk (1973) believed that this species overwintered in a larval diapause in South Dakota. H. pennsylvanicus readily oviposited n the crispers during October and eggs were found individually throughout the soil. This same observation was made by Kirk (1973) and Tomlin (1975). A total of 56 eggs was isolated in vials. Mean egg size before eclosion was, 1.73 by 2.56 mrn, a size increase of 18% over the size at oviposition (1.44 by 2.20 mm). Tomlin (1975) measured the eggs to be 1.6 by 2.5 mm at oviposition. Larvae were provided foxtail seeds which were often later found in tunnels the larvae constructed. Kirk (I 972b) also found foxtail seeds in tunnels, but none showed feeding damage. Head capsule widths of the surviving larvae were recorded and added to the field-collected information in Table I. Although the larvae of Am ra were not separated to species by Dr. Bousquet, we believe the larvae ofAm r  can be divided into two species based on the field from which 2The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 2https://scholar.valpo.edu/tgle/vol19/iss3/21986 THE GREAT LAKES ENTOMOLOGIST 149 Table I. Head-capsule width measurements, limits, and ratios of successive instars for selected earabid larvae found in pitfall traps in alfalfa, Lexington, KY. Species Instar N x ± SE (mm) Limits (mm) Ratio .~mara cllpreolata 1st 2nd 3rd 32 36 8 0.53 ± 0.01 0.75 ± 0.01 0.95 ± 0.02 0.34-0.56 0.64-0.83 0.90-1.05 0.70 0.79 Emrthrusif sodalis 1st 2nd 3rd 9 7 I 1.07 ± 0.04 1.63 ± 0.Q3 2.26 ± -0.90-1.36 1.51-1.70 0.66 0.72 Harpalui' pennsylmnicu5 1st 2nd 3rd 75 15 12 1.73 ± 0.01 2.34 ± 0.04 2.84 ± 0.05 1.36-1.92 2.11-2.56 2.64-3.17 0.74 0.82 Chlaenills tricolor 1st 2nd 3rd 31 8 8 0.69 ± 0.02 1.00 ± 0.03 1.38 ± 0.Q3 0.41-0.87 0.90-1.13 1.28-1.54 0.69 0.72 Scarites 5ubterraneus 1st 2nd 3rd 37 20 12 1.55 ± 0.04 2 39 ± 0.04 3.17 ± 0.05 L 17-1.88 2.03-2.64 2.94-3.43 0.65 0.75 Amara impuncticollis 3rd 22 1.21 ± 0.01 1.13-1.32 "Contains four head capsule measurements of 1st instars from laboratory-reared in addition to field-collected specimens. bContains 42 head capsule measurements of 1 st ins tars from laboratory-reared in addition to field-collected specimens. were trapped and the species of adults found there. All the larvae designated as A. implmcticollis Say were collected during June in a field where only adults of that species were represented in pitfall catches. Larvae of Amara cupreolata Putzeys were collected from a different field that had very few adult Amara belonging to other species. Larvae of A. cupreolata were present from late May through July. This species overn'inters as adults because adults were active very early in the spring. However, A. impuncticollis adults were not active until July, which was after the collection of larvae in June. This species probably overwinters in an immature stage. The molar-like shape of the mandibles suggests that larvae of Amara are omnivorous, as are the adults. The Chlaenius larvae were probably C. tricolor Dejean. These larvae have sickle-like mandibles adapted for piercing soft-bodied prey, as do other known members of this genus (Kirk 1972a). Larochelle (1974) surveyed the Chlaenius literature and believed C. tricolor adults to be omnivorous. These larvae must be very active foragers on the soil surface because large numbers of larvae were trapped in comparison to numbers of adults. First instars were active in June and July, second instars in July through September, and third instars in August and September. Some confusion exists as to the Scarites larvae. Blatchley (1910) recognized two North .-\merican species, S. subterraneus Fabricius and S. quadriceps Chaudoir, that he separated solely on the basis of size. Lindroth (1961) considered S. quadriceps to be a subspecies of S. subterraneus and we have followed his interpretation. Emden (1942) reported the mean second instar head capsule width of S. quadriceps as 2.39 mm; that corresponds exactly to our measurement (Table 1). First instars were found in June and July. but second instars were active from June through September. Most third instars were caught in August. 3Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: CarPublished by ValpoScholar, 1986150 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 The seasonality, abundance, and head capsule widths of the most abundant carabid larvae in Kentucky alfalfa presented here should aid future researchers in characterizing immature carabids found in many agroecosystems in the eastern United States. Additional studies are needed to characterize the abundance, seasonality, and feeding behavior of carabid larvae because these immatures remain a relatively unknown entity in most agroecosystems. ACKNOWLEDGMENTS Thanks are cxtended to Dr. Yves Bousquet, Biosystematics Research Institute, Agriculture Canada, for his identification of larval Carabidae. LITERATURE CITED Barney, R. J., S. J. Roberts, R. D. Pausch, and E. J. Armbrust. 1979. Insect predators of the alfalfa weevil and clover root curculio (Coleoptera: Curculionidae) during fall field reentry. Great Lakes Entomol. 12:153--155. Bechinski, E. J., and L. P. Pedigo. 1981. Ecology of predaceous arthropods in Iowa soybean agroecosystems. Environ. Entomol. 10:771-778. Blatchley, W. S. 1910. An illustrated and descriptive catalogue f the Coleoptera or beetles (exclusive of the Rhynchophora) known to occur in Indiana. Nature, Indianap­olis. Chu, H. 1945. The larvae of the Harpalinae unisetosae (Coleoptera, Carabidae). Entomol. Amer. 25:1-71. Dogger, J. R., and C. A. Olson. 1966. Larval characteristics of some North Dakota carabids (Coleoptera: Carabidae). Coleopt. BulL 20:91-96. Dritschilo, W .. and D. Wanner. 1980. Ground beetle abundance in organic and conventional com fields. Environ. Entomo!. 9:629-631. Dyar, H. G. 1890. The number of molts of lepidopterous larvae. Psyche 5:420-422. Emden, F. I. van. 1942. A key to the genera of larval Carabidae (Col.). Trans. Royal Entomo!. Soc. London 92:1-100. Goulet, H. 1976. A method for rearing ground beetles (Coleoptera: Carabidae). Coleopt. Bull. 30:33-36. __. 1979. Contributions of characters of larvae to systematics of Carabidae. pp. 205-208 in T. L. Erwin, G. E. Ball, and D. R. Whitehead (eds.). Carabid beetles: Their evolution, natural history, and classification. Junk Publ., The Hague. Holliday, N. J., and E. A. C. Hagley. 1978. Occurrence and activity of ground beetles (Coleoptera: Carabidae) in a pest management apple orchard. Canadian Entomol. 110:113-119. House, G. 1., and J. N. All. 1981. Carabid beetles in soybean agroecosystems. Environ. Entomol. 10:194--196. Kirk, V. M. 1972a. Identification of ground beetle larvae found in cropland in South Dakota. Ann. Entomol. Soc. Amer. 65:1349-1356. __. 1972b. Seed-catching by larvae of two ground beetles, Harpalus pensylvanicus and H. erraticus. Ann. Entomol. Soc. Amer. 65:1426-1428. __. 1973. Biology of a ground beetle. Harpalus pensylvanicus. Ann. Entomo!. Soc. Amer. 65:513-518. Larochelle, A. 1974. A world list of prey of Chlaenius (Coleoptera; Carabidae). Great Lakes Entomo!' 7:137-142. Lindroth, C. H. 1961. The ground-beetles (Carabidae, exc!. Cicindelinae) of Canada and Alaska. Part 2. Opusc. Entomol. (Supp!.) 20:1-200. Los, L. M., and W. A. Allen. 1983. Abundance and diversity of adult carabidae in insecticide-treated an  untreated alfalfa fields. Environ. Entomol. 12: 1068-1072. Morrill, W. L. 1975. Plastic pitfall trap. Environ. Entomol. 4:596. 4The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 2https://scholar.valpo.edu/tgle/vol19/iss3/21986 THE GREAT LAKES ENTOMOLOGIST 151 Thompson, R. G. 1979. Larvae of North American Carabidae with a key to the tribes. pp. 209-291 in T. L. Erwin, G. E. Ball, and D. R. Whitehead (eds.). Carabid beetles: Their evolution, natural history, and classification. Junk Publ., The Hague. Thompson, R. G., and R. T. Allen. 1974. Descriptions of larval Carabidae. I. Coleopt. Bull. 28:185-201. Tomlin. A. D. 1975. Notes on the biology and rearing of two species of ground beetles, Pterostichus melanarius and Harpalus pensylvanicus (Coleoptera: Carabidae). Cana­dian Entomol. 107:67-74. 5Barney and Pass: Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: CarPublished by ValpoScholar, 1986

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Pitfall Trap Collections of Ground Beetle Larvae (Coleoptera: Carabidae) in Kentucky Alfalfa Fields

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