Colorado Potato Beetle

Colorado Potato Beetle

Common Name: Colorado potato beetle

Scientific Name: Leptinotarsa decemlineata

Order: Coleoptra Family: Chrysomelidae

Life Stages: Complete metamorphosis (egg, larvae, pupae, adult)

Eggs:    Are bright orange, foot-ball shaped and found in

clumps of 20-60 on the underside of leaves. They hatch in 4-9 days.

Larvae: Are reddish, ½” long and humpbacked with 2 rows of black spots down the sides. They are found mostly near the hatching site or on the top of the potato plant. As they mature through the 4 molt (instar) stages, they tend to move farther away in search of more food.  This whole maturing process takes a mere 2-3 weeks. 

Pupae: Found burrowed in the soil near the potato plant, the pupae are oval and orangish in colour. The adult will emerge in 5-10 days. 

Adult: The adults are 3/8” long, yellowish-orange robust and oval insects. They have 10 black stripes down their elytra (leathery wings). Interestingly enough, the beetle overwinters as an adult and their emergence is more or less synchronized with potato plants.

Type of Damage: Both adults and larvae feed on their host plants’ foliage and stems. Adults usually cause less severe damage, except in cases where they eat through the stem of young host plants and cause the plant’s subsequent death. One beetle will not cause much damage; however, their high reproduction rates and subsequent unchecked eating often causes full defoliation of the host plants. 

Control Methods:

Cultural: There are three cultural control methods that work quite well. 1. Crop rotation, with a 0.5 km protection distance of susceptible crops, is known to have reduced the beetle populations by 95.8%.  2. Delaying your planting until later in the season or planting varieties that will produce earlier in the season (before beetle damage is significant) are two other good options. And 3. Plant a “trap” crop to seduce the insects and then destroy the trap crop. 

Physical: Digging small trenches around your crop at a 45 degree angle can trap the beetles (they usually walk to crops after spring emergence). Up to 95% of the beetles can remain trapped in these trenches. If dealing with a small number of plants, hand-picking of adults and eggs is also a viable option.

Biological: Many biological controls are not effective because of the early onslaught of beetle damage, however, the following creatures are predatory towards the Colorado potato beetle:  A blue-green ground beetle (Lebia grandis), predatory stink bugs, green lacewings, the spined soldier bug (Podisus maculiventris) and a tachnid fly (Myiopharus doryphorae). 

Chemical: The beetle quickly grows immune to pesticides, so most are not effective after a few years (i.e. Sevin). Also, only applications to young larvae are effective as eggs and pupae are protected and adults are very difficult to spray. The four chemicals still recommended, however, are Rotenone, a botanical insecticide (recently registered for food crops) produced upon extracts from the Neem tree, a fungus (Beauveria bassiana) and the natural bacteria product, Bacillus thuringiensis, var. tenebrionis.

Types of Plants Affected: Potato crops and other plants in the Solanacae family such as eggplant, ground cherry, tobacco, tomato, etc. Its first recorded host plant was the buffalo-bur.

Additional Information:

1.      The adult females can lay up to 500 eggs over a 4-5 week period.

2.      They are able to fly up to several kilometres to find a new host plant if need be.