{"id":2782,"date":"2019-05-22T00:05:10","date_gmt":"2019-05-22T07:05:10","guid":{"rendered":"https:\/\/depts.washington.edu\/hortlib\/pal\/pal-question-572\/"},"modified":"2023-08-04T10:03:17","modified_gmt":"2023-08-04T17:03:17","slug":"on-managing-weevils-in-the-garden","status":"publish","type":"pal","link":"https:\/\/depts.washington.edu\/hortlib\/pal\/on-managing-weevils-in-the-garden\/","title":{"rendered":"on managing weevils in the garden"},"content":{"rendered":"

What is the pest that eats little notches around my Bergenia<\/strong>
\nand Heuchera? What can I do to prevent this?<\/strong><\/p>\n

 <\/p>\n

It is possible your Bergenia and Heuchera are being nibbled by black vine
\nweevils or strawberry root weevils. Usually you would begin to notice the
\ndamage in mid-spring. The notches won’t kill your plants, but if you have
\na lot of black vine weevils and plants appear to be wilting, you may want
\nto attempt to control the larvae. Spraying beneficial nematodes
\n(Steinernema) on the surrounding soil may also help.<\/p>\n

Below are links to information about weevils:<\/p>\n

Black Vine Weevil<\/a> from UMass Extension<\/p>\n

Black Vine Weevils<\/a> from University of California’s Integrated Pest Management site<\/p>\n

Strawberry Root Weevil<\/a> from the Pacific Northwest Insect Management Handbook<\/p>\n

A document about Black Vine Weevil (and other root weevils) from Ohio State University Extension<\/a><\/p>\n

Excerpt:<\/p>\n

“Adults that feed along leaf margins produce typical crescent shaped
\nnotches. Careful searches should be made to try and locate specimens
\nsince several other weevils and some caterpillars can produce this same
\ntype of notching. Moderate to light notching seems to have little effect
\non plant health.<\/p>\n

“Black vine weevils are oblong oval in shape, about 1\/2-inch long and have
\na short, broad snout with elbowed antennae. The body is slate grey to
\nblackish brown and the wing covers have numerous small pits and short
\nhairs. This pest is difficult to distinguish from other Otiorhynchus
\nweevils. The strawberry root weevil is usually half the size of the black
\nvine weevil, and more brown in color. The rough strawberry root weevil is
\nonly slightly smaller than the black vine weevil but the collar just
\nbehind the head, the pronotum, is heavily pitted.<\/p>\n

“Female weevils emerge from soil pupation chambers late May to early July.
\nThese weevils must feed on plant material for 21 to 45 days before they
\nare ready to lay eggs. After the preoviposition period has passed, the
\nfemales place several eggs each day into the soil or leaf litter nearby
\nsuitable host plants. The weevils hide during the daytime at the base of
\nplants or in mulch and leaf litter near food plants. Adults may live 90
\nto 100 days and usually lay 200 eggs during this time. The eggs hatch in
\ntwo to three weeks and the small C-shaped, legless larvae feed on plant
\nrootlets. The larvae grow slowly over the summer, molting five to six
\ntimes. By late fall the larvae have matured and are about 5\/8-inch long.
\nThe mature larvae enter a quiescent prepupal stage in an earthen cell and
\npupate the following spring. A single generation occurs each year.<\/p>\n

“Strategy 1: Habitat Modification – Egg and larval survival is helped when
\nsoil moisture is moderate to high in July and August. Heavy mulches also
\nhelp maintain critical moisture levels. Remove excessive mulch layers and
\ndo not water plants unless necessary. Excessively damp soils in the fall
\nalso force larvae to move up the base of the plant where girdling can
\noccur. Properly maintain rain down spouts and provide for adequate
\ndrainage of soil around plants.<\/p>\n

“Strategy 2: Biological Control Using Parasitic Nematodes – The
\nentomopathogenic nematodes, Steinernema and Heterorhabditis spp., have
\nbeen effective for controlling black vine weevil larvae, especially in
\npotted plants. Sufficient water must be used during application to wash
\nthe infective nematodes into the soil and root zone. If the nematodes are
\nto be used in landscape plantings, remove a much of the mulch as possible
\nand thoroughly wet the remaining thatch and soil before and after the
\nnematode application. Applications of the nematodes in landscapes has
\nproduced variable results.”<\/p>\n","protected":false},"excerpt":{"rendered":"

What is the pest that eats little notches around my Bergenia and Heuchera? What can I do to prevent this?   It is possible your Bergenia and Heuchera are being nibbled by black vine weevils or strawberry root weevils. Usually you would begin to notice the damage in mid-spring. The notches won’t kill your plants, but if you have a lot of black vine weevils and plants appear to be wilting, you may want to attempt to control the larvae….<\/p>\n

Continue reading on managing weevils in the garden<\/span><\/a><\/div>\n","protected":false},"author":4,"featured_media":0,"menu_order":0,"template":"","keyword":[647,600,89,90],"class_list":["post-2782","pal","type-pal","status-publish","hentry","keyword-bergenia","keyword-heuchera","keyword-insect-pests-control","keyword-root-weevils"],"acf":[],"_links":{"self":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal\/2782"}],"collection":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal"}],"about":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/types\/pal"}],"author":[{"embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/users\/4"}],"wp:attachment":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/media?parent=2782"}],"wp:term":[{"taxonomy":"keyword","embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/keyword?post=2782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}