Striped cucumber beetles and Colorado potato beetles are two common garden pests that can wreak havoc on vegetable plants. While they may look similar at first glance, there are some key differences between these two beetles. Learning how to identify them is crucial for effective control in the garden.
Appearance
The striped cucumber beetle is identified by its greenish-yellow body with three distinct black stripes running lengthwise down its wing covers It has an oval or rounded shape and is about 1/4 inch long The head is black with visible antennae.
Meanwhile, the Colorado potato beetle has a more rounded body that is yellow-orange in color with five bold black stripes running longitudinally across the wing covers. Some individuals may have slightly reduced striping. This beetle grows up to 3/8 inch long. The head and antennae are also black.
Host Plants
Striped cucumber beetles, as the name implies, favor plants in the cucurbit family, which includes cucumbers, squash, pumpkins, and melons. However, they will also feed on beans, corn, and other vegetables.
Colorado potato beetles primarily target potato plants but are also problematic pests of tomatoes eggplants, peppers, and additional nightshade family crops. They rarely bother cucurbits.
Damage
The striped cucumber beetle affects plants in two ways. The adults chew holes in leaves flowers and stems. The larvae feed on roots after eggs are laid at the base of plants. This beetle also spreads bacterial wilt disease as it feeds. Leaves will wilt and turn brown or black. Entire vines can die off.
Colorado potato beetles are voracious leaf feeders, especially in the larval stage. They eat leaves down to the veins, leaving only a lace-like network behind. This damage can quickly defoliate and kill plants if left uncontrolled. The larvae also occasionally bore into potato tubers.
Distribution
The striped cucumber beetle is primarily found east of the Rocky Mountains in the United States and south-central Canada. It overwinters in plant debris before emerging in spring.
Meanwhile, the Colorado potato beetle can be found throughout most of the continental U.S., as well as southern Canada and Central America. It also overwinters before becoming active again in spring.
Control Methods
Handpicking adults, larvae, and egg clusters is one organic control option for both beetles, especially in small gardens. Row covers can exclude the pests before they reach plants. Beneficial insects like ladybugs will prey on eggs and larvae. Insecticidal soaps and neem oil also deter feeding.
For heavy infestations, pesticide sprays like carbaryl or pyrethrin may be needed to reduce beetle numbers, but should be used judiciously to minimize risks. Crop rotation is less effective with the Colorado potato beetle since it has a broader host range.
Key Differences
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Striped cucumber beetles have 3 black stripes while Colorado potato beetles have 5 stripes.
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Striped cucumber beetles favor cucurbits whereas Colorado potato beetles target nightshades.
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Striped cucumber beetle larvae feed on roots below ground; Colorado potato beetle larvae feed on leaves above ground.
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Striped cucumber beetles spread bacterial wilt; Colorado potato beetles do not transmit disease.
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Striped cucumber beetles are mainly eastern; Colorado potato beetles are found continent-wide.
Properly identifying whether striped cucumber beetles or Colorado potato beetles are attacking plants is the first step in managing these destructive pests in home gardens. Knowing host plants, damage symptoms, distribution, and life cycles aids in selecting appropriate organic or chemical control methods. Paying close attention to the subtle differences between these two beetles will lead to more effective protection of crops.
Biology of three-lined potato beetles Three-lined potato beetle larvae feeding on a leaf. Eggs can also be seen. Photo: David Cappaert, Bugwood.org
- It is unclear if three-lined potato beetles spend the winter as adults or pupae. We suspect they overwinter in the soil.
- Adults appear in the spring and feed on leaves.
- Female beetles lay eggs in clusters on the underside of leaves.
- Once larvae hatch, they also feed on leaves.
- The larvae protect themselves by cementing their feces on their backs.
- Larvae transform into pupae in mid to late summer, with most adults emerging in August.
- It is unclear whether this insect has one or two generations per year.
How to tell three-lined potato beetle from other insects Threelined potato beetle on a leaf
- The three-lined potato beetle is a little larger than 1/4 inch long.
- It has cream-colored to reddish-yellow wing covers with three black stripes running down its back.
- It has a reddish-orange prothorax (the area behind the head) with two small black dots on it.
- Three-lined potato beetle can be confused with a striped cucumber beetle but these two insects feed on different plants.
- Larvae are small with green bodies and shiny black heads.
- Eggs are elongated and orange.
Potato Beetle’s Vs. Liquid Sevin
FAQ
What is the difference between a potato beetle and a cucumber beetle?
Cucumber beetle: They look very similar to the potato beetles mentioned above, except they have yellow and black stripes and are just a tad longer in length. There are two species of the cucumber beetle: spotted and striped. The spotted species have 11 spots in the eastern US and 12 in the western US.
Are striped cucumber beetles bad?
Cucumber beetles can damage foliage and fruit. Striped cucumber beetles can transmit the bacterial wilt pathogen that can kill cucurbits. Cantaloupe and muskmelons are severely affected by bacterial wilt. There are nonchemical and chemical options available for managing cucumber beetles.
What is the difference between corn rootworm and striped cucumber beetle?
The Striped Cucumber Beetle, Acalymma vittatum (family= Chrysomelidae), also sometimes called a Corn Rootworm because the babies look like worms, is often a devastating pest species. The beetle is native to eastern North America and can produce multiple generations per year.
Do cucumber beetles eat potato leaves?
The spotted cucumber beetle has a wider host range and may also feed on more than 200 alternate host plants, including beans, corn, and potatoes. Both feed mainly on the leaves, pollen and flowers, but they will feed on soft fruits, leaving scars on the fruit.