9 Beetles Found In The Garden: Identification and Control

Most varieties of Beetles feed on developing crops and are harmful in garden soils. Although there are a small handful that are beneficial, they are a rare exception.

Identifying which beetles are attacking your garden is the first step in controlling them. Preventive measures can include permaculture tactics such as companion planting as well as other organic methods of control which are not only cost-effective but also more beneficial to the environment.

9 Types of Beetles Found in the Garden

  1. Flea Beetle
Diagrams and images of flea beetles

Flea Beetle is a generic name applied to many species of small jumping beetles commonly seen early in the gardening season. They are somewhat elongated to oval in shape and vary in color, pattern, and size. There are dozens of varieties.

Common Flea Beetle Types:

  • Desert Corn Flea Beetle
  • Pale Striped Flea Beetle
  • Potato Flea Beetle
  • Eggplant Flea Beetle
  • Spinach Flea Beetle
  • Striped Flea Beetle

They are difficult pests to manage causing headaches for the most avid gardeners, various varieties attack eggplant, seedlings of tomatoes, potatoes, peppers, radishes, and corn.

Cedarcide is an effective deterrent of flea Beetles and a large array of other insect pests.

2. Sap Beetles

Pictures of various sap beetles

Sap Beetles are mostly small black or dark insects that are flattened and broadly oval. Most feed on plant sap that exudes from wounds on ripe and decaying fruit or fungi.

Common Sap Beetle Types:

  • Dusky Sap Beetle
  • Picnic Beetle
  • Strawberry Sap Beetle

Harvest tomatoes, melons, berries and other produce as soon as they ripen. Remove any damaged, diseased, or overripe fruits and vegetables at regular intervals. The collecting of ripe and decomposing fruits and vegetables is needed to eliminate beetle food sources.

Egg and larvae of the sap beetle can be kept in check with  Neem Oil and /or predatory insects such as Lady Bugs.

3. Asparagus Beetle

Pictures of asparagus beetles

Adults are a blue/black beetle with a red underside and yellow spots. The larvae are a soft, green /Yellow grub. Both feed on asparagus spears by chewing the tips and spear surfaces which leads to scarring and staining of the spears.

Common Types of Asparagus Beetles:

  • Common Asparagus Beetle
  • Spotted Asparagus Beetle

Eggs are laid on developing spears with the eggs being small, elongated and black – sticking out lengthwise from the side of asparagus spears.

Early control of beetles is important to reduce feeding damage later.

Rotenone, Pyrethrum, malathion, and carbaryl are effective against asparagus beetles. Neem is most effective against the larvae stages only.

4. Colorado Potato Beetle

Pictures and diagrams of colorado potato beetles

A robust beetle with five yellow and black stripes on back. Larva is reddish-orange, humpbacked with two rows of black spots on each side.

They prefer to feed on potato, eggplant and tomato. Rotate these preferred hosts with other crops in alternate years.

Effective Predator insects are Lady Bugs which devour Colorado potato beetle eggs.

Bacillus thuringiensis a natural bacteria is highly effective against the Colorado Potato Beetle. It will control the early stages of the Colorado potato beetle and larvae. It is not as effective against adults. BT must be applied as soon as possible when the beetles or larvae are still young

5. Cucumber Beetle

Various pictures of cucumber beetles

There are two different types of Cucumber Beetle. The striped form and it’s cousin the spotted cucumber beetle also known as the southern corn rootworm. they are basically identical except that it features a dozen black spots instead of stripes. Another well-known family member is the corn rootworm.

Whether spotted or striped, both are the same size and the same, greenish-yellow color, and both dine on a wide variety of cucumber and related vegetables as well as various ornamentals , roses and dahlias for dessert.

Common Types of Cucumber Beetles:

  • Striped Cucumber Beetle
  • Spotted Cucumber Beetle
  • Banded Cucumber Beetle
  • Cucumber Beetle Larvae

Cantaloupe, squash, pumpkin, gourd, melons, other species of cucurbits., beans, corn, peanuts, potatoes, are also on it’s menu. What a balanced diet! Probably the most serious damage by cucumber beetles is the transmission of bacterial wilt. In the worst-case scenario this disease can wipe out your Garden. The striped and the spotted cucumber beetle both can carry the bacteria.

Damage caused by Cucumber beetles includes Seedling destruction, Flower & Foliage damage, Root Feeding and Disease transmission.

6. Harlequin Bugs

Pictures of harlequin bug.

Harlequin bugs are also known as the cabbage bug, calico back, and calico bug. The adult black, shield-shaped bug is covered with orange, red, and yellow markings. It varies in size but is generally no more than 3/8 inch.

The barrel-shaped egg, laid in clusters on crucifer foliage, is light gray to pale yellow with two black bands. The nymph is similar to the adult in coloration, but is smaller and lacks wings.

Found from coast to coast in North America, but no further North than Southern Ontario and Maine. It does its primary damage in the southern states.

Harlequin bugs will feed on squash, corn, bean, asparagus, okra, tomato, cabbage turnip, Brussels sprouts, cauliflower, cabbage, kale, kohlrabi, lettuce, collard, mustard, radish,

Neem Oil prevents the larvae from developing normally and is also a good alternative for later larval stages.

7. Squash Bugs

A picture of squash bugs.

Flat backed, winged, brown/ black, occasionally mottled with tan/gray or light brown.
Young squash bugs, are a muddled white to green/gray, with black legs. Newly hatched nymphs have a green abdomen, red legs, and antennae. Shortly after hatching (within a day), red parts become black.

Nymphs pass through 5 stages (instars) requiring 4-6 weeks before reaching maturity. Late instars are of a dark, greenish-gray color.

The squash bug is frequently misidentified as a stinkbug . Their appearance is similar and both emit a distinct foul “stink” either when crushed, or congregating in large numbers.

Eggs are laid on the undersides of leaves in clusters of a dozen or more . Egg laying continues until midsummer. The orange-yellow eggs, each about one-sixteenth of an inch in length, appear in neatly ordered rows . They gradually change to a bronze color before hatching.Only one generation develops each year and new adults do not mate until the following spring.

Squash bugs can be found clustered beneath damaged leaves, or in any protective groundcover. They feed by sucking sap from the leaves and stems while injecting a toxic substance into the plant causing a wilting known as Anasa wilt of cucurbits.

8. Tarnished Plant Bugs

Pictures of tarnished plant bugs

A common sap-feeding insect attacking a wide range of plants. Beans, beets, cauliflower, cabbage, chard, celery, cucumber, potato, turnip, salsify, and dill; apple, peach, pear, strawberry, blueberries and most other deciduous and small fruits.

It can cause considerable damage to vegetables and fruits by puncturing young fruits before they mature. These damaged areas do not develop along with the rest of the fruit/vegetable, resulting in misshapen produce.

The damage may range from slight deformation to complete loss . Adults and nymphs both inject poison into young stems, buds, and fruit. It sucks on blossom stems as well. They carry fire blight disease and infect plants as they feed. Black spots and pitting can be seen on the stem, tips, buds, and fruit.

9. Mexican Bean Beetle

An image of the mexican bean beetle.

Adults and larvae of this species will cause major crop damage to beans. They feed on both the leaves and bean pods. In heavy infestations, the tissue between the leaf veins may be completely skeletonized.

Adult bean beetles are pale yellow to copper colored with 16 black spots on their outer wings. They are sometimes mistaken for a lady bug. Adults lay egg clusters in early summer, the yellow eggs will appear on the underside of the leaves.

As the eggs hatch yellow larvae covered with black-tipped spines emerge and commence devouring plants. The larval stages are responsible for the greatest damage to bean crops. They feed on the underside of the leaves for four to five weeks before they pupate. Adult beetles emerge within a week.

Pyrethin is effective, but must be reapplied on a regular basis as it breaks down in sunlight quickly.

Beauveria bassiana  is a naturally occurring fungus that acts as a parasite on various insect species, bean beetles being one of these.