Lady Bugs: A Friend to Farmers
There seem to be lots of those red and black spotted insects active this year. From alfalfa fields to wheat crops, the landscape seems to be teeming with lady bugs. Most farmers and ranchers know lady beetles are a beneficial insect, but many may be unaware of all that they do.
The most abundant lady beetle, or ladybug, species in Kansas field crops is the convergent lady beetle, Hippodamia convergens. It is a native species. This lady beetle is recognizable by the two convergent white lines on the black portion of the body immediately behind the head. Aphids are the preferred food, although adults may supplement their diet with other prey items. Overwintered adults produce one generation in early spring that is typically completed around the time wheat is harvested, leading to the mass exodus of large numbers of beetles from maturing wheat fields. As fall brings cooler weather, females lay their bright yellow or orange eggs in clusters near aphid colonies to begin the next generation. They will remain dormant through winter months until they are awakened by the warm temperatures of spring.
Another common species is the twelve-spotted or pink lady beetle, Coleomegilla maculata. The adults are pink with six black spots on each wing cover. Aphids are also the preferred food of this species, but a very wide range of insect prey may be consumed. The larvae of this species are unique among lady beetles in their ability to complete development on an exclusive diet of pollen. Pollen is also attractive to adults and many can be found in corn fields at tasseling. They also like to feed on the eggs and small larvae of many moth species that are abundant in corn, including corn borers. This species is often abundant in proximity to water sources such as rivers and lakes. It hibernates in aggregations during winter months but, unlike the convergent lady beetle, probably continues to reproduce throughout summer months, typically producing 3 or 4 generations per year.
A species becoming increasingly common in the Midwest with the advent of soybean aphid is the multicolored Asian lady beetle, Harmonia axyridis. Adults are highly variable in coloration (pale orange to red) and spotting patterns (males often have none). The key to identifying this species is the prominent black ‘W’ on the part of the body behind the head. This invasive species is a voracious predator of aphids and many other insects, including the larvae of alfalfa weevil. Unfortunately, it will also feed on the eggs and larvae of many other lady beetles and has been associated with the declining abundance of a number of native species. This is a fact that has tainted its reputation as an otherwise effective biological control agent in many types of agricultural production. Another habit contributing to the potential pest status of this beetle is its tendency for entering houses in fall and winter, often forming large aggregations that can be very distressing to homeowners.
Lady beetles are a welcomed insect in crop fields across Kansas. They usually feed on aphids and a variety of other soft-bodied insects. Some will also feed on mites and the eggs and larvae of moths and beetles. Understanding all that they do to protect agricultural crops makes them easy to appreciate. They are truly a remarkable insect. Upon the next opportunity, really take the time to admire the lady bug.