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April Scouting Tips

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Insects to be on the Lookout for in April

Field and Vegetable Crops

Insect: Host(s)DescriptionTreatment Timing*
Black Cutworm and other Cutworms: Many crops but in particular cornMedium to large dark cater- pillars cut off plants at the base. Inspect newly planted seed beds and newly set plants. If more than 5% of the plants are cut, then control with an insecticide or bait is warranted.  
Root Maggots: Many vegetable and field crops, particularly  crucifer crops   White legless maggots feed on small roots and tunnel into large roots. Plants with damage fail to develop properly.   Usually a planting time soil insecticide is needed but a soil drench after plants have been set may be effective. Replanting is also effective because there is only one generation per year and no maggots infest the second planting.


Fruit Insects

Insect: Host(s)DescriptionTreatment Timing*
White Apple Leafhoppers: AppleLook for small, pale leafhoppers on the under- sides of leaves.  This will be the first generation.Check several trees and treat if a high density is found on all trees. If we have a dry spring, this pest may be a problem.
European Red Mite: Apple, pear, plum prune, and  many other trees and shrubs  Mites are very small and range from red to green. Foliage turns a sickly bronze color as if covered with dust.   Miticides can be used during the season but this mite is resistant to many miticides, so make sure that the chemical you use is effective. Otherwise use a dormant oil at the 1/2" green leaf stage.
Spotted Tenti- form Leafminer: AppleYoung mines are serpentine changing to oval. As the larvae get older they form the leaf into a tent- like structure.Treat young mines with Vydate or Lannate if more than 1 mine per leaf on average.


Ornamental Insects

Insect: Host(s)DescriptionTreatment Timing*

Bagworm: Conifers, maples sycamores, box- elder, and many others 

Caterpillars form "bags" around their bodies made of silk and plant debris.  They overwinter as eggs in the bags; the eggs hatch in late May and early June.

Pick off and destroy all bagworms now and/or treat with an insecticide in mid- June. Early next spring pick off all bags you can find. 

Boxwood leafminer: Boxwood 

Adults are out April to early May. Infested leaves often appear  blistered and discolored.

Apply insecticides for adults; apply systemic insecticides in early to late June to control larvae.

Boxwood Mite: Boxwood

White and gray stippling on the upper surface of the leaves.

Treat in early May with a miticide.

Boxwood psyllid: Boxwood 

Resemble aphids and are covered with a white cottony material. They feed on the undersides of the leaves.

Spray in mid-to- late April when growth has started.

Cutworms Many non- woody plants 

Medium to large dark cater- pillars cut off plants at the base. Inspect newly planted seed beds and newly set plants.

If more than 5% of the plants are cut, then control with an insecticide or bait is warranted. Reduce weed growth; cutworms are attracted to weedy areas.

Eastern Tent Caterpillar: Many fruit trees, but in particular cherry   

Look for conspicuous egg masses circling twigs. These egg masses will be black in color and quite shiny as if varnished.  The small black hairy caterpillars will hatch out in April and feed on the newly emerging leaves.

Pick off egg masses before they hatch.  Treat with an insecticide as soon as the leaves have emerged enough to retain the insecticide.   

Iris Borer: Iris, native blue flag     

Larvae feed below the soil level on the rhizomes and feeding damage is sometimes not apparent until the plant dies or the leaves wilt. Bacterial soft rot often follows borer damage.

Sprays are recommended for application in  early April. Important to remove and burn dead leaves,  dried rhizomes and damaged plants.

Juniper Scale: Junipers   

Crawler stage is from April 5-22 and June 5-20. Scales have an elongate white covering with a yellow cap at  one end.

Treat April 10-15 and/or June 10- 15  

Pine bark aphid: Eastern white,  Scotch, Austrian, and sometimes  other pines

The cottony masses that the insect produces are conspicuous even at a distance and are usually seen in bark crevices and  bases of needles.

Treat: April, late June, mid-August.  

Pine Needle Scale: Scotch, mugo, and  Austrian pine, some other conifers but usually not damaging

Crawler stage is from April 20-30 and July 10-20. Scales are white, elongate- narrow in front and broad in back.  

Treat May 5-20  and/or July 15- 20    

Southern red mite: Holly, pyracantha, azalea, rhodo- dendron, camellia, and other broad- leaved evergreens

Damage is seen as finely stippled leaves with a yellowed, chlorotic, or russetted appearance.  

Treat: late April to early May and late September to mid- October.  

Spruce Mite: Arborvitae, spruce, juniper, hemlock

Small mites, 1/50" long, cause a yellow stippling on the needles and die- back of lower branches.

Spray with a miticide in mid-May and early fall.

Virginia Pine Sawfly: Virginia pine primarily, also short leaf and loblolly  pine

Larva is green-gray with black stripes and a black head capsule. Treatment is usually only needed on high value trees with prior history of infestation.

Spray mid-April.    

White peach scale: Peach, locust, ash, pecan, mulberry, apple, and many other trees and shrubs

Crawler stage: April 25- May 15, July 1-15,  August 20 - Sept 15 Female scales are white and circular in shape, males are elongate.

Treat: May 1, July 1-15, August 20- Sept. 15  

White Pine Aphid: Eastern white pine      

Look for overwintering eggs on the ends of the needles; eggs are shiny black and as many as 26 may be found on one needle.  W.P. aphids produce large amounts of honeydew which provides an excellent growth medium for black sooty mold on the needles and branches.  Sooty mold is the most conspicuous indication of aphid infestation. 

Aphids will be scattered and more abundant in some places than others. Spot treat when and where you find aphids.  Aphids will probably be in damaging numbers in late April- early May.     

White Pine Weevil: Eastern white pine, Norway spruce, and other pines

Symptoms: resinous bleeding on the 8 to 10 inches of stem below the terminal bud and death of the upright leader.

Treat: late-March and early April.   


* See Virginia Pest Management Guides for recommendations on insecticides and rates. Use insecticide applications only when high population levels demand control action. Most plants can support small populations of pest insects.