August 17, 2007    No. 25

Too late to ………………………..

Spray for bagworms – Bagworms have essentially completed their current-season feeding activities. Up to this point, the bag remained attached to the host plant by a feeble/thin silken thread while the withdrawn bagworm was “resting” and/or undergoing a molt between instars. A sure sign that bagworms are preparing to pupate is the highly visible silk tie that firmly holds the bag in place.

Beginning in another 4-5 weeks, male bagworm moths will emerge and mate with the plump, egg-filled female who will then commence to depositing her overwintering eggs within her pupal case.

The eggs are nestled among soft body hairs. All of this is contained within her tough/thick silk-lined bag.

Especially where bagworm populations are high and hand-removal of bags is impractical, IT IS RECOMMENDED THAT people pull out their 2008 calendars and circle (in “red”) May 15. This will alert them to prepare for 2008’s bagworm activities. And, during the winter, study Extension Bulletin MF-728, Bagworms. Hard copies are available at local County Extension Offices. Electronic versions can be accessed (and downloaded, if desired) by visiting: http://entomology.ksu.edu  and clicking to Extension, and then to Publications.

Spray for elm leaf beetles – Inquires are being received about “dead elm” trees. While certainly Dutch elm disease may be responsible for killing elm trees (American elm is especially susceptible), many of the reports are related to Siberian elm which are common throughout Kansas. In most of these instances, the “brown” elm trees are very much alive. Their dead appearance is due to the cumulative feeding damage of first and second generation elm leaf beetle larvae. Elm leaf beetle larvae feed the protective epidermal tissues on lower leaf surfaces. Once removed, the leaves become desiccated, turn brown and die. Spraying now would not restore a trees green appearance. Rather, allow the remaining larvae to complete their feeding and join the ranks of those that have already pupated. Newly emerged adults will form the overwintering population. Despite the current stark appearance of elm trees, they are very much alive, and the intact axillary buds will produce next year’s flush of new foliage.

Hard copies of Extension Bulletin MF-2392, Elm Leaf Beetles are available at local County Extension Offices. Electronic versions can be accessed (and downloaded, if desired) by visiting: http://entomology.ksu.edu  and clicking to Extension, and then to Publications.

Spray for tobacco and tomato hornworms ……. As is common at this time of year, reports are filtering in regarding “big green worms with tail spines” eating tomato plants. By the time tomato and tobacco hornworms are detected, they are nearly full-grown and getting ready to pupate. Thus, the damage is done and there is little point in applying insecticidal sprays to kill them. The thought that you can prevent next year’s bout of hornworms by eliminating the current worms is erroneous ---- they are akin to a few grains of sand in the Sahara Desert. Unless one feels an absolute need to remove (hand pick) of kill (spray an insecticide) the larvae, simply allow them to complete their feeding cycle.

Despite their different names, tomato and tobacco hornworms have similar seasonal life histories, feeding habits and host preferences. Light trap catches of moths indicate that the tomato hornworm is more common. Yet, most larval reports are of tobacco hornworms.

Generally speaking for both species, their overall background color is a bright green although there are “darker forms”. Larvae can be identified by their body patterns and the color of their “horns”. Differentiation between the two? Tomato hornworm larvae possess a black “horn” and 8 stripes which hook backwards (thus somewhat appearing as a chevron). Tobacco hornworm larvae have a red “horn” and 7 diagonal stripes on each side of their body.

Bob Bauernfeind

Sunflower Moth

I received a report this week from southeast Kansas of continued high head moth counts, indicating that fields entering the bloom stage still need to be scouted for this pest. This field had reportedly already been sprayed once and a pheromone trap still collected 35 moths in one night less than a week after the first treatment. This was thought to be a result of uneven blooming in the field and heavy moth pressure in the area.

Phil Sloderbeck

Spider Mites

Hot dry weather in western Kansas has allowed spider mites to explode in the last few days. With corn maturing rapidly it will probably soon be time to just let the mites run their course. Most of the mites are twospotted spider mites which are very difficult to control in the hot dry conditions and with the corn almost mature the returns to spraying will be negligible. If the hot weather continues we can probably expect to see mites develop in other crops such as sorghum and soybeans where control could be even more of an issue due to the limited number of treatment options.

Phil Sloderbeck

Aphids in Sorghum

Light numbers of greenbugs and a few yellow sugarcane aphids have been reported in western Kansas. In recent years the greenbug has not been a serious problem, but always deserves watching. Texas has been reporting significant yellow sugarcane aphid populations this summer so keep watch for this bright yellow to light green aphid with short, stiff hairs.

Insect Diagnostic Report for August 2 – August 15

    8/2 -- Crawford Co; pyralid moth in field
    8/2 – Brown Co; oak lacebugs
    8/3 – Riley Co; prairie robber fly in yard
    8/3 – Leavenworth Co; moth pupae in sunflowers
    8/3 – Ecuador; Platycoelia spp. scarab beetles / grubs in strawberries
    8/3 – Anderson Co; katydid/longhorned grasshopper frass from silver maple
    8/7 – Virginia Tech; ground beetles in alfalfa purchased from KS
    8/13 – Riley Co; cobweb spider
    8/13 – Sedgwick Co; woolly oak galls
    8/13 – Ottawa Co; honeybees
    8/13 -- Allen Co; spined micrathena orbweaver spider, staphylinid beetle
    8/13 – Crawford Co; corn earworm moth, various other insects in trap
    8/13 – Leavenworth Co; spider mites and aphids on honeysuckle
    8/13 – Bourbon Co; cottony taxus scale
    8/13 – Rawlins Co; spider mites on green bean
    8/13 – Barton Co; spider mites on tomato
    8/13 – Leavenworth Co; euonymus scale
    8/13 – Leavenworth Co; spider mites on tomato
    8/13 – Neosho Co; oak lace bug
    8/13 – Dickenson Co; spider mites on viburnum
    8/13 – Dickenson Co; spider mites on fire bush
    8/14 – Riley Co; fungus gnats on potted plants
    8/14 – Dickenson Co; horsehair worm
    8/14 – Mitchell Co; earwigs on peach tree
    8/14 – Shawnee Co; nymphalid caterpillars on plant
    8/14 – Johnson Co; psyllids by house

Elizabeth Murray

Sincerely,

Robert J. Bauernfeind                                           Elizabeth Murray
Extension Specialist                                              Entomology Diagnostician
Horticultural Entomology                                      phone: 785/532-4739
phone: 785/532-4752                                          email: emurray@ksu.edu
email: rbauernf@ksu.edu

Phil Sloderbeck
Extension Specialist, Entomology
Southwest Research and Extension Center
Garden City, Kansas
phone:  620-275-9164
email:  psloderb@ksu.edu