Ladybugs are insects, and this means they undergo a complete metamorphosis: hatching from eggs into larvae, then transforming into pupae, and finally emerging as adult beetles. When they first emerge from their snug pupal cocoons, they look like ladybugs in shape and size, but their coloration isn’t yet set; they will typically be a pale orange-yellow or a grayish color. You see, when they first emerge their wing covers, also known as eletra — their shells or modified wing covers if you will — are wet and quite soft. It’s nothing a few hours in the sun won’t fix, though.
As they dry in the sun their adult color darkens into a reddish-orange or black. This is typical. Do note that there are beetles that are yellowish and other colors as well, but let’s focus on the red and black predatory beetles for now. What do these colors mean? Is their any significance to these colors? Maybe. I’ve noted that red-hued ladybugs are often aphid predators, whereas blackish beetles often feed on scale (and other pests).
Do red ladybugs tend to be aphid predators?
- Hippodamia convergens: As everyone knows, these beetles are typically red to orange with black spots and they feed on aphids. Being opportunistic, though, they will feed incidentally on other soft-bodied insects and even a mite.
- Harmonia axyridis: These also feed on aphids, at least the red ones do. H. axyridis are commonly called “Multi-colored Asian Ladybeetles” some are red with black spots, or no spots at all, while others are black with red or yellow spots, or, again, no spots at all. The black ones tend to feed on scale more predominantly than the red ones do.
- Coleomegilla maculata: also known as the twelve-spotted ladybeetle, is yet another example of a reddish aphid predatory beetle.
Do black ladybugs tend to be scale predators?
- Lindorus lophanthae: This small black beetle (with orange thorax) feeds on various scale insects from various scale families. Small but versatile.
- Cryptolaemus montrouzieri: These well-known beetles, which also go by the nickname “Crypts,” are well known mealybug destroyers — mealybugs are a scale family — and will also feed on other scale species. These beetles, like the ones above have an orange thorax.
- Cybocephalus nipponicus: Small, black, and predatory, these beetles feed on specific scale species like the euonymus scale.
- Chilocorus kuwanae and Chilocorus stigma: These both feed on various scale insects. The former also feed on euonymus scale.
Other Black Beelte Prey
But black ladybugs do feed on other pests, too.
- Dephastus cataliniae: These glossy specs feed on a wide variety of whitefly species. Do note that whiteflies are very closely related to scales.
- Pseudoscymnus tsugae: These tiny black beetles feed on hemlock woolly adelgids specifically.
- Stethorus punctillum: These fuzzy, tiny black beetles feed on spider mites so they are really far removed from the others.
Is There Something to This?
This red beetle – black beetles dietary observation is purely speculative and based on a small number of predatory beetles. Can you think of other examples that might prove or disprove this observation? Can it be supported or is it just a minor coincidence?