Page 14 - Free State Winter 2022 - Website Version

TOTAL PLANT MANAGEMENT (Continued)

Kirk 'Floyd of KDrone company preparing a DJI spray drone for the bagworm trials. Undergraduate students place bagworm cages on 'Green giant' arborvitae in the nursery for our trial of
low-risk pesticides applied using a drone.
Economic Impact to Nursery and Landscape disperse to surrounding plants by spinning a silken thread
Industry and ‘ballooning’ on the wind. Once a suitable host is
found, the caterpillar begins feeding and incorporating
The wide host range, high female fecundity, and method
of dispersal by wind, make bagworm a major problem in material into its bag, which it constructs with pieces of
nurseries and in landscape settings. Damage to foliage twigs, leaves, and silk (Peterson 1969). Only the head
can be extensive. Less than 10% damage on woody plants and the thorax emerge from the anterior end of the bag,
is tolerated by consumers (Lemke et al. 2005). During the so that the caterpillar can feed and move along plant
summer months, as few as four bagworm larvae can material.
cause a four-foot arborvitae to be unmarketable for sale Trial Using a Drone that Sprays: Materials and
(Sadof and Raupp 1987). Methods
Adult bagworms We applied reduced-risk products or biopesticides (See
Table 1.0.) with a sprayer mounted on a drone (Model DJI
Adult bagworms will often go unnoticed in the nursery
and landscape, especially the female, because she Agras MG-1P). These insecticides were applied in two to
is enclosed in her bag and inside of her pupal casing three passes over rows of Thuja ‘Green Giant’. The rows
throughout her life. The adult female’s wings and were 120 feet long and four feet wide. Ten plants with
appendages are greatly reduced to vestigial mouthparts two plants buffer between, were randomly selected in
and legs, small eyes, and no antennae or wings. The each row for pre and post counts. The trees were two
female remains in a caterpillar-like state, mates, and then meters (approx. six feet) tall, a meter and a third (approx.
the bag becomes essentially an egg-filled sac. The male four feet) wide and planted on two-meter (approx. six
bagworm emerges as a free-flying moth that is hairy and feet) centers. Treatments were applied on 7 July 2021 and
charcoal black. Neither the male nor the female adult insecticide efficacy was evaluated as percent mortality on
feeds. The female lives a couple of weeks, while the male 20 July (13 days after treatment, DAT).
lives only one to two days (Rhainds et al. 2009). After Bagworm neonates hatched from eggs collected in bags
mating, the female lays a large egg clutch (500-1,000 from last year’s untreated trees. These neonates fed on
eggs) inside of her pupal case enclosed within her bag. untreated arborvitae foliage, in plastic observation cages
The eggs are smooth and cylindrical in shape and laid in until they reached 2nd – 3rd instar. Treatments were
a mass that is covered in a waxy, tuft-like layer (Peterson applied using the drone with the attached sprayer and
1969). Bagworm eggs will overwinter. allowed to dry for an hour. Then student interns added
the bagworms to a mesh bag placed over the treated
Bagworm Larvae
branches, confining the bagworm larvae to a treated
Hatching larvae are small (under 2 mm long) and often branch. One end of the mesh bag was cable tied closed
14 WINTER 2022 • Free State News