Description
Although C. maculatus is commonly referred to as a weevil, they lack the distinctive snout of weevils and, in fact, belong to a different group, the bruchid beetle, a subfamily of Chrysomelidae beetles. It can be distinguished from other bruchid beetles by its more elongated body and red-brown coloration as an adult. The beetle's elytra are short in comparison with the rest of its body and do not cover the last segment of the abdomen. The average body length of an adult beetle is 4–6 mm, though beetles that experience restricted nutrients in their larval stages can be much shorter. The average body mass of an adult is 4–6 mg, with female beetles generally being slightly larger than the males.
The beetles are sexually dimorphic, which means their sex is easily determined. Males tend to be smaller and possess a more rotund shape than the female. Additionally, females have dark stripes on the dorsal side of the abdomen. This gives the impression of a white stripe down the middle of the abdomen.
The eggs of C. maculatus are translucent before hatching and are 0.6mm in length. The eggs are small, flat and off-white once the larva have hatched from the egg.
The larva of C. maculatus is curved, white, and has a small head.
There are two morphs of C. maculatus: the dispersal form and the sedentary form. Both morphs are capable of flight, but the dispersal form is more likely to take flight than the sedentary form. While both forms are still sexually dimorphic, the visual differences between the sexes tend to be less obvious in the dispersal morph. The dispersal morph develops when there is a high concentration of larvae in one area. The dispersal morph lives longer than the sedentary morph and has lower fecundity. In particular, it lays fewer eggs and fewer of the eggs it lays reach adulthood. Scientists speculate that the dispersal morph continuously colonizes new areas, while the sedentary morph remains in its current environment.
Read more about this topic: Callosobruchus Maculatus
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