Insects To Watch Out For

May 18, 2011

Since most gardens are being planted or already growing, I thought I would help people prepare and watch out for specific insects.  This is a summary of insects to watch out for.

Wire worms – Wireworms live in the soil and can eat the seeds or small plant roots causing the need to replant.  They occur early spring and often are problems in areas turned from sod into a garden.  The treatment is to have insecticide treated seed or apply an insecticide when planting.  An interesting fact is the adults are click beetles.  Catch a click beetle and have fun.

Flea beetles – Flea beetles often are in large numbers about the same time plants emerge from seed.  They are 1 to 2 mm in size, black and jump or fly away when disturbed.  They suck juice from the small plant causing small injured areas.  Enough injured areas severely retard plant growth or kill the plant.  Treatment is an insecticide treatment.

Cutworms – Cutworms usually cause damage early spring.  Damage is recognized as plants that have been chewed on or chewed off at or just above ground level.  They also cause local spot damage in lawns.  They do their damage at night hiding in soil or thick vegetation during the day.  They can be controlled with most insecticides.

Aphids – Aphids love sucking on young tender tissue.  They are usually up to 1/8 inch long, often green to pink and have very soft bodies.  The garden plant most loved by aphids is the rose, where it is usually on the new growth near and on a developing rose bud.  They also are pests of many tree species and a few other garden plants.  They can be a little difficult to control due to large numbers.  Most pesticides control aphids but some aphids have resistance to some insecticides.  Insecticidal oils and soaps are often effective.

Colorado potato beetles – They are a pest on potatoes, tomatoes, and egg plants.  They overwinter in soil and come out when plants are small.  They are about 3/8 inch long as adults with orange bodies and yellow & dark brown longitudinal stripes on the hard shell wing covers.  The larvae are orange and through instar stages grow to about the size of adults.  They simply chew up the vegetation.  They are resistant to most insecticides.  Product containing Merit may work but some locations have resistance to Merit product also.  A new product containing clothianidin may be available for gardeners in a year or two from Green Light. 

Tomato hornworms – They eat all parts of the tomato plant.  They are worms with a horn on the tail end.  They start very small but can grow as large as your finger.  Large hornworms can cause a lot of damage very quickly.  They are very hard to find but occur in small numbers and can be picked off one and a time and disposed of.  Most insecticides are effective in killing the worms.

Cabbage butterflies – The cute little white to yellow butterflies lay eggs that become cabbage or broccoli worms.  Another similar pest is diamond back moths.  Their eggs also hatch and become worms in cole crops.  Cabbage and broccoli worms are generally a mid-summer to fall insect problem.  They are easy to control with vigilant spraying.  Another method of control is to plant a very early crop and harvest before the butterflies become a problem.  Bt insecticides such as Bt Worm Killer or DiPel work very well on worm pests.

Thrips – Many species of thrips occur and infest many species.  The western flower thrip is a severe pest of many flowers including roses.  Chili thrips are a newer pest, infesting peppers.   Onion thrips are common in onions and often cause early death of onions.  This is one of the tougher pests to control because of the large numbers of thrips.  Many thrips have true resistance to many insecticides.  New insecticides containing Safari are now available and give control from the inside out.  Unfortunately, they are not labeled for food use.

Corn earworms and borers – They infest sweet corn and the borers are a major pepper pest.  Adults lay eggs that eat their way into corn ears chewing on my favorite garden crop, sweet corn.  They also drill a little hole in pepper fruits just below the cap often causing the pepper fruit to spoil.  Sweet corn is often sprayed commercially every 2 to 3 days to stop this pest.  Any corn ear with a worm ruins the ear.  Commercially, one infested ear in a hundred ears is not acceptable.  To treat sweet corn in the garden, spray or dust the ears at least once a week starting as soon as the silk appears for three weeks.  Most insecticides will control corn earworms.  Insects are worse the later in the season the crop matures.  When consumers have the opportunity to grow genetically altered Bt sweet corn, you will never see a corn earworm again until resistance occurs.

Cucumber beetles and squash bugs – This is a group of insects that chew or suck on the vines of watermelons, cucumbers and squash.  Often they transmit a virus or bacteria that cause the infected vine to wilt.  A fine line exists between controlling this insect with insecticides and letting bees and other pollinators pollinate the flowers without being killed.  There are many insecticides that work.  As the season progresses these bugs get worse.  Most insecticides will control these insects.  You do need regular sprays.

The new Brown Marmolated Stink Bugs – Good Luck.  This will be covered in a later post, but a lot of insecticides will kill it.

There are way too many insects to discuss in one post.  Sorry if I missed yours.