9th Annual Fall Tiger Beetle Trip: Day 2

I didn’t mind my late start to the 9th Annual Fall Tiger Beetle Trip—my first stop on Day 1 was only ~30 miles south of St. Louis, so I would get in a good chunk of collecting on the day even though I didn’t leave the house until after noon. I didn’t find the longhorned beetle, Ataxia hubbardi, that I was looking for (and haven’t seen now for more than 23 years), but I did manage to see good numbers of the always impressive jewel beetle, Dicerca pugionata, and a very large, impressive male tarantula (walking on water!). After that, however, the trip would make a very early diversion from its original itinerary. The light drizzle that pestered me all day at Victoria Glades steadily turned to rain as I traveled south towards northern Arkansas, and checking the weather forecast further reduced my optimism as rain was predicted for the next two days. The tiger beetles that I so enjoy are creatures of the sun, and rather than spend the next two days being chased around the Ozark Highlands looking for dry ground, I made a snap call and bolted straight for northwestern Oklahoma, where I had planned to go after two days in northern Arkansas and southwestern Missouri (collecting populations of the disjunct Prairie Tiger Beetle, Cicindelidia obsoleta vulturina, for molecular analysis by a collaborator). It was hard driving—five hours on dark, rainy roads to get to Springfield for the night, and another six hours to get to my first destination; Gloss Mountains State Park. I have been here several times over the past few years, discovering resident populations of three very interesting tiger beetles: Cylindera celeripes (Swift Tiger Beetle), Dromochorus pruinina (Frosted Dromo Tiger Beetle), and Amblychelia cylindricollis (Great Plains Giant Tiger Beetle). I did not expect to see any of these species on this trip, as they are all summer species (although I did hold out hope that I might find a few stragglers, especially of the last one). Instead, I was playing a hunch that Cicindela pulchra (Beautiful Tiger Beetle) might be found here because of the similarity of the Red Hills habitat to that just north in south-central Kansas where the species famously occurs (MacRae 2006).

Gloss Mountains State Park, Major Co., Oklahoma

It was worth the drive, as driving west got me out of rain and once past Enid, OK the cloud cover began to break up. By the time of my early afternoon arrival at Gloss Mountains State Park, skies were blue and temps were in the low 70s. Unfortunately, despite these perfect conditions my hunch that C. pulchra might occur here did not prove to be true. Nevertheless, it was a fruitful day as I collected two larvae each of all three of the above tiger beetle species (including 2nd instars of the presently undescribed C. celeripes and 3rd instars of the frightfully enormous A. cylindriformis—what an impressive creature!), photographed several beetles on yellow asteraceous flowers—two of which I show below, saw another male tarantula, and found an adult female of the truly impressive lubber grasshopper, Brachystola magna, that will become my daughters’ newest pet and has already been named ‘Bertha’ by them. My wanderings through the prairie at night with a lamp on my head did not produce any A. cylindricollis adults, but the views of the Milky Way in the dark, cloudless sky above amidst the overwhelming silence of a vast prairie cloaked in darkness were nothing short of spectacular.

Caps of gypsum over soft red clay have resulted in a landscape of flat-topped mesas.

Here are two of the beetles that I photographed on the day. This first one is a soldier beetle (family Cantharidae) that is a dead ringer for Chauliognathus limbicollis. I couldn’t find any indication that this species is known from Oklahoma—all of the BugGuide photos of this species were taken in Arizona, while the admittedly outdated key to species in the tribe Chauliognathini (Fender 1964) gives only more western states (Arizona, Colorado, New Mexico and Texas) in its distribution. Still, I saw the species not uncommonly as it fed on yellow asteraceous flowers.

Chauliognathus limbicollis on yellow asteraceous flower | Glass Mountains, Oklahoma

Another beetle that I photographed on flowers of Heterotheca subaxillaris (stiffleaf false goldenaster) was this small blister beetle (family Meloidae) that seems to be a member of the great genus Epicauta. I won’t even attempt a species ID due to the size and difficult taxonomy of this genus; however, this was the only example of this species that I saw amidst abundant individuals of another solid gray species that seemed to prefer the flowers of Gutierezzia sarothrae (broom snakeweed) over H. subaxillaris.

Epicauta sp. on Heterotheca subaxillaris flower | Glass Mountains, Oklahoma

During the day, I found some trees infested with jewel beetle larvae (presumably in the genus Chrysobothris), so I will return in the morning of Day 3 to harvest the wood and bring it back to put up in rearing containers in an attempt to rear out the adults. Afterwards, I will be off to my next destination—Alabaster Caverns State Park.

REFERENCES:

Fender, K. M. 1964. Tbe Chauliognathini of America North of Mexico (Coleoptera—Cantharidae), Part 2. Northwest Science 38(3):95–106.

MacRae, T. C. 2006. Beetle bits: The “beautiful tiger beetle”. Nature Notes, Journal of the Webster Groves Nature Study Society 78(4):9–12.

Copyright © Ted C. MacRae 2012

9th Annual Fall Tiger Beetle Trip: Day 1

Once again, I have embarked upon my Annual Fall Tiger Beetle Trip, this being the ninth consecutive year that I have done such a trip. Unlike previous editions, however, the quarry on Day 1 (Sept. 15) was not a tiger beetle but a longhorned beetle. Ataxia hubbardi is not uncommon in the eastern and central U.S. and breeds in the living tissues of a variety of herbaceous plants, but especially certain species of Helianthus, Ambrosia, and Silphium in the family Asteraceae. I was hoping to see a distinctive population of this beetle that is associated with prairie dock (Silphium terebinthinaceum) in the dolomite glades just south of St. Louis. This population is interesting because individuals are smaller, darker, and narrower in form than is typical for the species, and I would like very much to get some photographs of the adults, which seem most abundant in the fall, on the tall flower stalks of their host plant.

Victoria Glades Natural Area | Jefferson Co., Missouri

I first discovered the population many years ago—back in the 1980s when I visited one particular glade, Victoria Glades Natural Area, almost weekly over a period of several years. I left Missouri for a few years in the early 1990s but returned in 1995, and during my absence fire was implemented in Victoria Glades and other glades in the area as a management practice for controlling invasion by woody plants (primarily eastern red-cedar, Juniperus virginiana). While the use of fire has certainly done much to restore the glades and improve its floral diversity, it seems more than coincidental that insect abundance and diversity on the glades is only a fraction of what I observed during my pre-burn collecting in the 1980s. There are a number of beetle species that I found at the glade historically that I have not seen now for more than 20 years; one of which is this distinctive population of A. hubbardi.

Prairie dock (Silphium terebinthinaceum) – host for Ataxia hubbardi

The prairie dock plants were at the height of bloom, but the flower stems seemed shorter and the normally large, spatulate basal leaves of the plants generally smaller than typical—perhaps a result of this summer’s severe drought. How such conditions affect the beetles is unknown. The day was also rather cool due to unbroken cloud cover and light drizzle, with temperatures in the low 70s during my visit. I spent the better part of two hours inspecting the stems of every prairie dock plant that I encountered and did not see a single beetle, so it has now been 23 years—almost a quarter century—since I’ve seen this once fairly common species at the glade. Can I prove that fire management has extirpated the beetle? No—populations might have been knocked down by the drought, or maybe the adults hide on cool, cloudy, drizzly days. Still, the pattern is too consistent to ignore, and I become increasingly worried that a special feature of these glades has now been lost.

Ninebark (Physocarpus opulifolius intermedius) – host for Dicerca pugionata

On the other hand, another quite rare beetle that I encountered abundantly at Victoria Glades in the past seems to have rebounded from its long absence—the jewel beetle Dicerca pugionata. This beautiful beetle is associated with the scraggly clumps of ninebark (Physocarpus opulifolius intermedius) that hang on in the moist toe slopes of the glades. I wrote about this species earlier this year after re-discovering it in the glades; however, I couldn’t resist taking a few more photographs of this stunningly gorgeous species. This species also makes its appearance in the fall as well as spring, and in the two hours I spent searching I counted 13 beetles—more than I’ve ever seen on any one day. Interestingly, most of these were associated with a stand of plants in an area at the south end of the glade that I had never searched before and that appears not to have been subjected to fire management (cedar removal has been effected instead with a chain saw). Only a few of the beetles were found in the much more abundant plants growing in the area of the glade I am more familiar with and that has obviously been subjected to repeated burning. It’s not proof, but I’m just saying…

Dicerca pugionata on ninebark branch.

Adult beetles are colored almost precisely the same as the bark of their host plant.

More even lighting in this face shot compared to my previous attempts.

The cool temperatures and light drizzle were not conducive to much other insect activity, but while crossing the small, shallow creek that separates the south end of the glade from the main glade, the biggest male tarantula (Aphonopelma hentzi) that I have ever seen caught my attention as it crossed the creek. Situated only 30 miles south of St. Louis, Victoria Glades must represent the northeastern limit of distribution for the species, and although I once saw a tarantula crossing the road very near to this location, this is the first tarantula that I have actually seen in the glades that lie so close to St. Louis. Males are famous for their fall wanderings, presumably in search of the females that tend to stay within their burrows. This male was missing part of one of its hind legs but otherwise appeared quite healthy and robust. I hope he succeeds in finding a mate and sires many offspring and is not discovered by any of the poachers who regularly scour the glades and steal its more unusual inhabitants—the glades have already lost enough of their unique residents…

Can you find the tarantula crossing the creek? (Hint: 0.60X, 0.37Y)

Male Aphonopelma hentzi | Jefferson Co., Missouri

Copyright © Ted C. MacRae 2012

A classic fall ‘bycid

In eastern North America, autumn is the beginning of the end for most insect groups. Preparations for winter are either complete or well underway—eggs have been laid, nests have been provisioned, and larvae (hopefully) have eaten well enough to endure the long, cold months that lie ahead. But for a few insects, fall is just a beginning. Triggered by cooler temperatures, shortened daylength, and invigorating rains, adults of these insects burst forth under crisp, blue skies to feed amongst a plethora of fall flowers or prey upon other late season insects before the advancing cold, finally, forces a close to the season. As a beetle man, my favorite fall insects must be the “fall tigers” (i.e., tiger beetles) that come out in force and zip across barren sand dunes or bask on exposed rocks of dolomite glades. My fall insect collecting focuses almost exclusively on these insects, since my other favorite groups (jewel beetles and longhorned beetles) are, for the most part, restricted in their adult activity to the spring and summer months and long gone by the time fall rolls around. There are, however, a few longhorned beetles that buck the normal spring/summer rule for the family, namely species in the genus Megacyllene. The most commonly encountered of these is Megacyllene robiniae (locust borer), and anyone who has examined goldenrod (genus Solidago) and its profuse blooms during the fall has likely encountered this familiar beetle with its narrow, alternating, zig-zag bands of black and yellow.¹ I have seen this species many times and in many places; however, I still always enjoy seeing it anew in the field each fall—perhaps as some sort of confirmation that the fall season truly has arrived.

¹ If you see a “locust borer” in the spring, it is actually the closely related Megacyllene caryae (hickory borer), while further west in the Great Plains during fall you might find Megacyllene comanchei.

Megacyllene decora (amorpha borer) | Mississippi Co., Missouri

Another species in the genus that is far less commonly encountered, however, is Megacyllene decora (amorpha borer). I have encountered this stunningly beautiful species in only a handful of locations in Missouri (MacRae 1994)—all where stands of its larval host plant, Amorpha fruticosa (false indigo), grow in association with goldenrod and snakeroot (genus Eupatorium). These sites are primarily in the big river valleys of the state (Missouri and Mississippi Rivers), although I have found at least one site in the prairies of west central Missouri. Earlier this summer while traveling through the southeastern lowlands of Missouri, I noticed a stand of native Hibiscus growing within a wet ditch along the edge of a small city park and stopped by to look for the even rarer Hibiscus-associated jewel beetle, Agrilus concinnus (MacRae & Nelson 2003, MacRae 2006). While I did not find that species, I did notice fairly good numbers of A. fruticosa plants along the edge of the ditch as well and young goldenrod plants that had not yet reached flowering stage. At that moment I knew I had a good potential site to look for M. decora and made a mental note to stop at the site again later in the season when goldenrod began to bloom.

The species is distinguished from related species in the eastern U.S. by its wide black and yellow bands.

Last week I returned to the site to find not only goldenrod in its earliest stages of bloom, but an even greater number of Eupatorium serotinum plants already in bloom. I wanted to photograph the beetle, of course, but what I was really hoping for was to find and photograph the beetle on the stems of its Amorpha host plant (I have only seen this once before—all other sightings of the beetle have been on flowers of goldenrod and snakeroot). I approached each Amorpha clump cautiously and searched the stems carefully, also keeping an eye on the goldenrod and snakeroot blooms as I moved from one clump to the next. After searching a number of clumps, I finally found the adult shown in these photos. Fortunately, I knew from previous experience in collecting these beetles that they are not a particularly wary species (few aposematically- or mimetically-colored beetle are), so I was able to get a number of good photographs before I (stupidly) bumped the beetle with the diffuser over my flash heads and disturbed it.

”Blue sky” settings: ISO160–200, 1/200 sec, f/14–16, camera pointed near (not at) the sun.

It would be another half hour before I would find a second beetle, and in total on the day I saw only three (all on Eupatorium). This and the very early stage of the goldenrod blooms suggests to me that the beetles were just beginning to emerge—over the next few weeks I am sure they will become more numerous at the site, so I may yet have an opportunity to photograph one on its larval host plant when I pass by the area in a couple of weeks.

Normal ”normal” full-flash settings: ISO100, 1/250 sec, f/16.

REFERENCES:

MacRae, T. C. 1994. Annotated checklist of the longhorned beetles (Coleoptera: Cerambycidae and Disteniidae) known to occur in Missouri. Insecta Mundi 7(4) (1993):223–252.

MacRae, T. C. 2006. Distributional and biological notes on North American Buprestidae (Coleoptera), with comments on variation in Anthaxia (Haplanthaxia) viridicornis (Say) and A. (H.) viridfrons Gory. The Pan-Pacific Entomologist 82(2):166–199.

MacRae, T. C., and G. H. Nelson. 2003. Distributional and biological notes on Buprestidae (Coleoptera) in North and Central America and the West Indies, with validation of one species. The Coleopterists Bulletin 57(1):57–70.

Copyright © Ted C. MacRae 2012

Not quite a one-shot

This little jumping spider (~8 mm in length) was in one of my soybean fields in west-central Illinois last week. She(?) was quite fidgety and kept jumping from the leaf on which I found her as I tried to carry the leaf out of the field to a more open and convenient place  to take photographs. Once I got out to the grassy field border, I managed to get one photograph (not shown but similar to this one) right before she jumped off the leaf yet again. However, I was able to find her and coax her back onto the leaf for this last shot before she jumped off again—never to be found again! I presume this spider belongs to the genus Phidippus based on the cephalic tufts, and within that genus maybe a species in the P. clarus group (corrections welcome!).

When I look at insect macrophotographs, I like to do reverse engineering on the lighting to figure out what was the flash/diffuser setup. I have a few different diffusers that I use depending on which lens I’m using and how important the photographs are. In this case, I was taking photographs of soybean insects for work purposes and didn’t bother putting on the larger concave diffuser that I use when I’m really concerned about getting more even lighting. Instead, I was just using my snap-on Sto-Fens+Gary Fong Puffers. The difference between these two diffuser setups and their effect on lighting is minor in many cases, but when photographing very shiny surfaces (such as the eyes of this spider) the differences are much more apparent, and it is obvious from this photo that I was using a twin flash unit with separate diffusers on each flash head.

There is one more feature apparent about the lighting in this photograph—note that the “left” flash head appears much more diffuse than the “right” flash head. This is because the right diffuser had actually fallen off of the flash head without me noticing (also never to be found again!). As a result, the light from only one of the flash heads was diffused, while that from the other hit the subject in all its harsh glory. I don’t really like the twin highlights that are the hallmark of twin macro flash units, and if I had known I was going to be photographing jumping spiders when I was in the soybean field I would have gone ahead and used my concave diffuser. I’ve also learned, however, that great photographs are not something that I can expect to pop off while concentrating on other activities—I need to concentrate fully on the photographs and spend a good amount of time doing it until I feel like I’ve gotten the shots that I want. I never really liked the Sto-Fen+Puffer diffusers, as they were only marginally better than no diffuser (and this photograph shows it), so losing one of them might be a blessing in disguise as now I’ll be motivated to try out some of the many other diffuser ideas I’ve been toying around with but never really taken the time to sit down and try them out.

Copyright © Ted C. MacRae 2012

The very dirty tiger

Ellipsoptera cuprascens (Coppery Tiger Beetle) | Mississippi Co., Missouri

In my post Very wary tigers!, I lamented my inability to photograph one of our state’s less commonly encountered tiger beetles, Ellipsoptera cuprascens (Coppery Tiger Beetle), on an open Mississippi River beach under a blazing sun. There are solutions to such problems, however, one of which is the use of blacklights to attract the beetles at night when cooler temperatures and readily available prey make the beetles much more approachable. Of course, this only works for those certain species that are attracted to blacklights, of which fortunately E. cuprascens is one, and not long afterwards I was able to photograph individuals of this species that came to a blacklight placed further south along the Mississippi River in New Madrid Co., Missouri. The photos were adequate, but none were what I would consider a true winner, so when I found the species again while blacklighting at another Mississippi River beach in southeast Missouri I continued with my attempts to photograph them.

Heavy lime coating the antennae must feel to this fellow like like breathing in concrete does to us!

The species was much less abundant this time, and none of the few individuals that showed up at the light actually spent any time on the ground where I could take reasonably natural looking photographs. This time I decided to look for them along the beach away from the light and succeeded in finding a few. As is typical, the first several that I tried to photograph were too wary to approach, but I’ve learned to keep trying until I find that one (slightly) more cooperative individual. As I crossed over the concrete boat ramp I saw one that seemed not at all flighty. I’ve seen the ubiquitous Cicindela repanda commonly on concrete boat ramps, so I checked carefully to be sure it wasn’t that species, and after confirming its E. cuprascens identity I began the slow, cautious approach that ended with me flat on my belly and the camera lens inches from the beetle. Nighttime photography is tricky because… uhm… it’s dark, and I don’t find my flash unit’s focusing lamps all that helpful (they tend to time out right before I’ve composed the shot to my satisfaction). Instead, I place my headlamp on the ground and position it so that it continuously illuminates the subject so I can concentrate on getting multiple shots without having to constantly divert my attention to the focusing lamp button. The concrete was hard, and my elbows were mad at me for a time afterwards, but the beetle was generously cooperative and took on some very nice poses during the session, leaving me with the impression that I’d gotten that “perfect” shot as I walked back to the blacklight.

The obligatory face-shot—especially stark in its white lime surroundings!

Sadly, these photos are far from perfect. Their composition is good, as is their focus and lighting and the natural-looking poses that I captured. But the beetle is absolutely filthy! I didn’t realize it at the time, but apparently its wanderings across the decaying lower reaches of the concrete boat ramp resulted in a thick coating of lime on just about every part of its body. Now, few tiger beetles that I photograph are perfectly clean and spotless, and although a few grains of sand around the mouth or on the legs are tolerable, I am not above cloning out debris that detracts from the beauty of the beetle—especially when it is on the eyes or its shiny, glabrous dorsal surface. This beetle, however, is simply beyond repair. I’m by no means a Photoshop expert, but I’m not sure even the most fluent PS whiz could fix this beetle. So, my quest for the “perfect” E. cuprascens photo will continue…

Copyright © Ted C. MacRae 2012

Life at 8X—Guide to lepidopteran eggs on soybean

Most of you are aware of my passion for beetles, but in reality that is just my evenings-and-weekends gig. By day, I am an agricultural entomologist conducting research on insect pests of soybean. I’m not sure how many latent soybean entomologists there may be among readers of this blog, but for this installment of “Life at 8X” I thought it would be interesting to feature eggs of several of the more important lepidopteran species that infest soybean in the U.S. Soybean is primarily a New World crop, and of the many lepidopteran species that attack soybean on these two continents, most belong to the great family Noctuidae (owlet moths). The species shown here include the most important species in North America, and in some cases South America as well.

See this post for details on photographic technique; however, note that most of the photos in this post that were shot at 8X have been cropped slightly (~10–15%) for composition (should I call this post “Life at 9X”?).


Anticarsia gemmatalis. Velvetbean caterpillar (“oruga de las leguminosas” in Argentina; “lagarta-da-soja” in Brazil) has long been the most important lepidopteran soybean pest throughout the New World. In North America its attacks are confined to the lower Mississippi River delta and southeastern Coastal Plain, but in South America nearly 100% of the soybean growing area is subject to attack. Eggs of this species are laid almost exclusively on leaf undersides throughout the canopy and are intermediate in size compared to the other species shown below (~7,000 eggs per gram). They are distinctive in their slightly flattened spherical shape and turn pinkish as they age and the developing larva takes form inside the egg.

Anticarsia gemmatalis—velvetbean caterpillar


Chrysodeixis includens (=Pseudoplusia includens). Soybean looper (“oruga medidora falsa” in Argentina; “lagarta falsa-medideira” in Brazil) was until recently primarily a North American pest with the same southern occurrence as velvetbean caterpillar. In recent years, however, it has gained importance in Brazil and northern Argentina as well, with its impact magnified by the capacity to develop resistance against most of the insecticides that have been used to control it. The egg of this species is quite small (~10,000 eggs per gram) and are are irregularly spherical with a somewhat translucent, crystalline appearance. Like velvetbean caterpillar, eggs of this species are laid almost exclusively on the leaf undersides, but the moths exhibit a clear preference for the middle or upper canopy depending upon plant growth stage.

Chrysodeixis includens (= Pseudoplusia includens)—soybean looper


Helicoverpa zea. Soybean podworm is better known in other crops as corn earworm, cotton bollworm, or tomato fruitworm (a testament to its polyphagous nature), and in South America the common names are even more diverse depending on both crop and country (“gusano bellotero,” “gusano cogollero del algodón,” “gusano elotero,” “isoca de la espiga en maíz,” or simply “bolillero” in Argentina; “lagarta-da-espiga-do-milho” or “broca-grande-do-fruto in Brazil). While it has long been considered a secondary pest of soybean in North America, recent years have seen a marked increase in its incidence across the mid-south growing areas. Unlike the above two insects, larvae of this species feed not only on foliage but also directly on pods, typically breaching the pod wall and consuming the developing seeds inside. This method of feeding not only causes direct yield impacts but also affords some protection to larvae from insecticide applications.

Also unlike the first two insects, eggs of this species can be laid anywhere on the plant—leaves (upper or lower surface), petioles, stems, pods, and even flowers. The eggs are rather large compared to the other species shown here (~3,500 eggs per gram) and assume a distinctive barrel shape when laid on the leaf. The creamy-white coloration, often with a light brown ring below the apex, is also distinctive compared to the previous two species. Eggs laid on pods tend to be attached to trichomes (hairs) rather than the pod surface, in which case they take on an almost perfectly spherical shape.

Helicoverpa zea—soybean podworm

Helicoverpa zea eggs on soybean pod


Heliothis virescens. Like the previous species, tobacco budworm has only recently gained attention as a pest of soybean. This importance, however, seems to be confined to Brazil (where it is known as “lagarta-das-maçãs”), while in North America it is usually found in combination with H. zea at minor levels. This is bad news for South American farmers; like soybean looper, tobacco budworm has developed resistance to all the insecticides that have been used against it in significant quantities. The oviposition and feeding behaviors of this species are very similar to those of H. zea, with eggs again laid on all parts of the plant and being very similar in appearance to those of H. zea except their slightly smaller (approx. 5,000 eggs per gram). In practical terms, eggs and young larvae of H. virescens and H. zea can be reliably distinguished only through species-specific immunoassay (Greenstone 1995) or feeding disruption bioassay using a diagnostic concentration of Bacillus thuringiensis ( Bailey et al. 2001).

Heliothis virescens—tobacco budworm

Heliothis virescens eggs on soybean pod.

As with H. zea, H. virescens eggs laid on pods tend to be stuck to hairs and assume a spherical shape.

This H. virescens egg has apparently died—note the shriveling and uniform black coloration.


Spodoptera frugiperda. Fall armyworm is a minor pest of soybean that rarely reaches economically damaging levels. However, its incidence in South America (where it is called “oruga militar tarde in Argentina and “lagarta-militar” in Brazil) has increased somewhat with the adoption of no-till cultivation of soybean. The species prefers grass hosts, but when these are knocked down by applications of post-emergence herbicides the larvae then move onto the soybean plants and continue feeding. Unlike any of the above species, eggs are laid in distinctive masses that are covered by abdominal setae and wing scales for protection. These eggs are also small (~8,500 eggs per gram), exhibit much finer and more numerous ridges than the above species, and are often colored orange, pink, or light green.

Spodoptera frugiperda—fall armyworm

Individual eggs inside the mass are covered by abdominal setae and wing scales.


REFERENCES:

Bailey, W. D., C. Brownie, J. S. Bacheler, F. Gould, G. G. Kennedy, C. E. Sorenson & R. M. Roe. 2001. Species diagnosis and Bacillus thuringiensis resistance monitoring of Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) field strains from the southern United States using feeding disruption bioassays. Journal of Economic Entomology 94 (1):76–85.

Greenstone, M. H. 1995. Bollworm or budworm? Squashblot immunoassay distinguishes eggs of Helicoverpa zea and Heliothis virescens (Lepidoptera: Noctuidae). Journal of Economic Entomology 88(2):213–218.

Copyright © Ted C. MacRae 2012