Today we focus our attention on the Large Cabbage White, an insect that anyone with a vegetable garden knows well and fears. This species of moth is particularly attracted to cauliflowers, black broccoli, and cabbages. In short, all vegetables that we are about to cultivate in the autumn season. Let’s learn to promptly recognize the large cabbage white so that we can implement a biological defense strategy, allowing us to effectively control the spread of this annoying and harmful insect in our crops.
Here are the characteristics of this insect.
The Large Cabbage White
The adults lay their eggs on the underside of the leaves of cruciferous plants, which are usually abundant during that period.
After a period of approximately ten days, the eggs hatch, and the larvae of the first generation come to life and then pupate again.
Generally, in the month of July, the adults appear again, in what is called the second flight. Through mating, they give rise to the second generation, and so on.
Depending on the climate, the large cabbage white can complete up to four generations in a year. Therefore, its presence can extend until late autumn.
Damages caused by the Large Cabbage White
Being widespread throughout the national territory, we can find the large cabbage white even at altitudes above 2000 meters above sea level. Given its high fertility, it causes some concern, also because it is present throughout the year, except during the winter season when it hibernates.
As the common name suggests, the large cabbage white is a moth particularly attracted to cabbages. By cabbages, we mean cauliflowers, black broccoli, cabbage, and, in general, all cruciferous vegetables.
The damage is caused by the feeding activity of the larvae, which eat and chew the leaves of the cabbages, sparing only the central veins of the tougher leaves.
This voracious activity can compromise the balanced development of the plant, and if perpetuated in the early stages of growth, it can lead to the end of the crop.
Another factor of danger is that the larvae often act in groups and very quickly, requiring timely identification and defense.
Compared to other Lepidopteran species, such as the tomato leaf miner that we have encountered in this article, fortunately, the biological defense against the large cabbage white is more straightforward.
Tomato Leaf Macerate
First and foremost, it is highly sensitive to the macerate of tomato leaves and females, which we have studied in a previous article.
When the large cabbage white larvae come into contact with this natural compound, they literally jump away from the leaves, avoiding it. Therefore, the tomato leaf macerate can be used both preventively and during an infestation.
It is recommended to apply it either in the evening or at dawn, times when the larvae are most active.
During the central hours of the day, especially if the temperatures are high, the larvae prefer to take refuge in the soil and then resume their activity when it cools down.
Also, pay attention to wetting the underside of the leaves, where the large cabbage white larvae tend to cluster.
Bacillus thuringiensis variety kurstaki
Another method of biological defense against large cabbage white larvae is Bacillus thuringiensis variety kurstaki.
As we know, Bacillus thuringiensis is much more effective against young larval stages rather than fully developed larvae. Naturally, given its high selectivity, it is totally ineffective and harmless to adult butterflies.
Therefore, it is necessary to understand the right time to intervene with this type of product to avoid unnecessary applications.
In this case as well, we recommend applying it during the cooler hours of the day. This not only targets a larger number of larvae but also slows down the high photolability (rapid degradation) of Bacillus thuringiensis (as we have extensively discussed) when exposed to sunlight. If you want to purchase the product, you can find it here.
Remember that this product, which is entirely natural, is not considered a phytopharmaceutical.
Another factor that makes the large cabbage white less harmful than other species of Lepidopterans is the presence of many natural predator insects, which help control the population.
In particular, hymenopterans and dipterans with various action mechanisms contribute to limiting the spread of the large cabbage white. Let’s see the main ones.
First and foremost is the well-known hymenopteran Apanteles glomeratus, which we see in the photo below in the adult stage. However, it is not the adults that feed on large cabbage white larvae. It is the larvae themselves of this endoparasitoid hymenopteran that parasitize (i.e., feed on) the large cabbage white larvae, as seen in this video.
The hymenopteran oophagus Trichogramma evanescens. The term oophagus refers to insects that lay their eggs inside the eggs of other insects, making them egg parasites.
Lastly, we have Phryxe vulgaris, a larvivorous dipteran, also a parasitoid of large cabbage white larvae.
- Cabbage moth (Mamestra brassicae) from Michigan State University: This resource discusses the cabbage moth, which is highly polyphagous, known to feed on more than 70 plant species from 22 families. Caterpillars prefer to feed on cruciferous plants.
- Imported Cabbageworm / Cole Crops / Agriculture from University of California Agriculture and Natural Resources: This resource provides information about the imported cabbageworm, which is the larval stage of the cabbage white butterfly. The adult cabbage butterfly is white to pale yellowish with a wingspan of 1.5 inches and has one to four black spots on each forewing.
- Cabbage White Butterfly | College of Agricultural Sciences from Oregon State University: This resource provides information about the cabbage white butterfly, a common insect in gardens or on farms. It associates with broccoli, cauliflower, and other cabbage family plants.
- Caterpillars on cole crops from University of Minnesota Extension: This resource discusses the most common caterpillar pests of cole crops, including the imported cabbageworm, cabbage looper, and diamondback moth. The imported cabbageworm is the most common.