Growers and field reps throughout the region have been noticing issues with seed maggots. Similar to root maggots, these are the immature form of a certain type of fly (Diptera: Anthomyiidae: Delia spp.).
There are three species, in particular, that can be devastating in vegetable crops. The first, cabbage maggot (D. radicum) is well-known and tends to infest brassicas only. Use this link for more info on cabbage maggot.
“Seedcorn maggot” is the common name for what is actually a complex of two species – D. platura and D. florilega. “Bean seed fly” is another commonly used name for adults. These two species are remarkably similar, both as larvae and adults. For adult flies, color is variable and one must examine leg hair length and placement. Maggots are indistinguishable, even by experts.
Complaints so far have come from parsnip and snap bean fields, but dry beans, corn, peas, and squash growers should take note. If emergence is low, scout 2-ft row sections. Look for damage to seeds and white, tapered maggots. Maggots are legless and have a blunt posterior.
PHOTOS ABOVE ADAPTED FROM: Savage, J., Fortier, A-M., Fournier, F., Bellavance, V. 2016. Identification of Delia pest species (Diptera: Anthomyiidae) in cultivated crucifers and other vegetable crops in Canada. Canadian Journal of Arthropod Identification No. 29: June 29, 2016. doi:10.3752/cjai.2016.29
Brooks, A. R. 1951. Identification of the Root Maggots (Diptera: Anthomyiidae) Attacking Cruciferous Garden Crops in Canada, with Notes on Biology and Control. Can. Entomol. 83(5): 109-120.
Higley, L. G. and L. P. Pedigo. 1984. Seedcorn Maggot (Diptera: Anthomyiidae) Population Biology and Aestivation in Central Iowa. Environmental Entomology. 13(5):1436-1442.
Larvae of various Tortricid moths (Lepidoptera: Tortricidae) are well-known pests to fruit and nut growers, but less considered in vegetables. Here is a quick list of some economically important species in this group:
Light Brown Apple Moth (Epiphyas postvittana)
Fruittree Leafroller (Archips argyrospila)
Codling Moth (Cydia pomonella)
Filbertworm Moth (Cydia latiferreana)
Strawberry Fruit Worm aka Omnivorous Leaftier (Cnephasia longana)
These small, bland colored moths are nearly undetectable in the landscape, but their larvae can cause billions of dollars of economic damage. Leaves are rolled or tied to provide shelter for developing larvae. Crop damage from this group can occur ‘from root to fruit’.
Another attention-grabber headline this month is the hatch of periodical cicadas in the eastern US. “Brood IX” is a 17-year assemblage that was expected, but there are “stragglers” from other groups of 13-year cicadas that are actually 4 years early. This year is unusual because the groups consist of many different species (all in genus Magicicada) and appear to be overlapping geographically. Confused yet? Me too, so I refer you to http://magicicada.org/magicicada/ if you’re interested.
Sounds are produced by specialized structures called tymbals, and can exceed 100 decibels! If you’ve never been lucky(?) enough to hear one, enjoy this video clip:
Cicadas are not ‘locusts’ ( which are a behavioral adaptation of grasshoppers). They’re more closely related to leafhoppers and spittlebugs.
Common cicadas have life cycles between 3 and 5 years. Nymphs (immatures) live underground and feed on tree roots.
If you see a green cicada, it is not a periodical species.
Emergence in the PNW may be related to rainfall: Chatfield-Taylor, W. and Cole, J.A. 2017. Living rain gauges: cumulative precipitation explains the emergence schedules of California protoperiodical cicadas. Ecology 98: 2521-2527.
We do, in fact, have cicadas in Oregon, but they do not occur at nuisance levels. There are ~ 30 species in our region; one of the most encountered is Okanagana oregona (pictured at right).
1 1/4″ to 2″ long with a striped abdomen, orange head, and black eyes
Predator of many large-bodied insects (grasshoppers, beetles, etc.)
Potential serious threat to honeybees
Ground-nesting, active from May to August
Detected in August 2019 British Columbia (eradicated); 4 confirmed sightings in Washington state to date; 0 confirmed sightings to date in Oregon.
Although AGH may have just hit headlines, there are a number of regional experts who can offer advice, answer questions, and field suspected reports of sightings. Please reach out if you are concerned. Early detection is key to limit the effects of invasive species.
This is a summary of an article published in the Winter 2020 issue of the Oregon Small Farm News. The article was written by Dr. Toshihiko Nishio and translated and edited by Shinji Kawai and Abigail Hunter, OSU Dept. of Horticulture. The article is available as a .pdf by using the link below.
In 1967, an ocean vessel was in the East China Sea conducting standard atmospheric and marine environment monitoring when, all of a sudden…
Little did the ship’s crew know – that experience would help scientists learn more about a very serious pest problem in rice. In fact, rapid invasions of planthoppers is thought to be one of the major causes of historical famines in Japan.
Ryoichi Kishimoto, who worked at a local agricultural research station formed a group to intensively study the planthoppers. They set up light traps, pan traps, and even windsocks to monitor at different locations throughout the region. In 1971, Kishimoto published his theory about long-range migratory patterns of the pest, which ignited international interest.
20 years after the original observation, another researcher from the same experiment station proved that the planthopper’s migration corridor includes a low-level jetstream from southern China to western Japan. This is how they are able to travel such massive distances in just a few days, and why they would’ve been observed by the ocean vessel.
Some growers tend to think of birds as chronic annoyances. Solutions range from preventative tactics (netting and birddogs) to scare tactics such as artificial predator calls and driving around the farm firing empty shells at murders – sound familiar?
But a new study suggests that certain birds can – and should – be welcomed as a part of an overall sustainable farming strategy. The link below explains:
The email that went out to subscribers Monday clarified that yes, we are done monitoring and reporting for the 2019 season. You can read that message here.
But please do continue to visit this blog for these and other updates:
Summarizing 2019 pest trends
A comprehensive written report will be available at the vegetable grower’s meeting and OPVC website by Jan 2020.
Investigating why corn earworm was so minimal in W. Oregon but very abundant E. of the Cascades and also in the midwest.
Cabbage looper outbreak: if it affected load rejections; possible prediction of outbreaks; how new methods of counting became necessary due to 1200+ moths per trap (see photo below)
Continued armyworm trapping
Cooperators in Tillamook county will continue to operate pheromone traps and scout fields through October because fall activity is common.
Trap counts are updated each week http:// beav.es/ZY3 and we are in the process of mapping them to examine if any geographical patterns are evident.
23 years of a darn-solid phenology dataset is nothing to scoff at. I have spoken with some of you about collaborating on a journal article. Dan would be proud, and I…well..need to. Maybe we’ll have enough rainy days this winter to actually accomplish it. Contact me if you’re interested.
We have received many emails this week about ‘home invasions’ of odd-looking bugs. In each case, the culprits were boxelder bugs. Although easily recognized as adults, the partially mature phase (nymphs) can be unfamiliar.
Nymphs and adults aggregate in large groups, especially on light-colored homes with a warm-facing side. The concern for damage on ornamental or fruit trees is low. Rather, these are considered a nuisance pest. The sheer and sudden numbers of them is what causes calls to come in.
Remember to subscribe to receive up-to-date information via email! We alert you of insect pest activity for nearly half the year (24 weeks), the service is currently free, and we promise to not bother you for the other 28 weeks, nor share your email address.
Notable trends during the week of June 24th include:
Cabbage Looper moth counts continue to be extremely high, we are likely seeing the 2nd generation, which is considered the most damaging for brassica crops.
Armyworms have wide host ranges but can be especially damaging in grasses, pastures, and field crops.
One species, in particular, seems to be booming this year. It is called the “Thoughtful Apamea“, which is closely related to glassy cutworm, but habits and host range are largely unknown.
Conversely, True Armyworm is well-studied and we have been collaborating on a project to monitor them in Tillamook County. So far, counts are low, but if you’re interested, trap counts will always be posted here: https://beav.es/ZQM
Beneficial Insects include pollinators, predators, and parasitoids that provide some type of ecosystem service. As natural enemies of pests, their activity tends to lag slightly. We have noted an increase in Syrphidae and Tachinidae flies this week, as monitored by passive sampling techniques.