The Red Milkweed Beetle participates in sexual reproduction during the early summer months of the year (Reinhartz, 2014). What makes this organism different from most other arthropods is that the males are more cautious when choosing a mate than the females (Lawrence, 1986). Males demonstrate direct competition and choice for mates, which is more unusual for arthropods.  There is more choosiness over females with which to mate when there is an abundance of females to choose from. In contrast, males become more competitive when there are less females available to mate with (Lawrence, 1986). Male Red Milkweed Beetles tend to be more likely to end mating sessions than females, and many mating sessions are terminated by other males wanting to mate with that specific female (Droney, 2010). It has been proven that male T. tetrophthalmus will mate for a longer period of time and initiate mating sooner with females who have physically larger bodies (Droney, 2010). The bigger the female’s body is, the more larvae that can be produced each day during the lifetime of that individual (Lawrence, 1990). This is a major reproductive strategy; if a female is large, she is more likely to pass on her genes. When a female Red Milkweed Beetle mates more often, she produces more fertile eggs than those who only mate once during their lifetime (Lawrence, 1990). Females show no specific size preferences towards the males they mate with (Lawrence, 1986). Unlike many organisms, female Red Milkweed Beetles do not use pheromones to attract mates (Reinhartz, 2014). Male beetles simply fly to different milkweed plants to find suitable mates. Each male and female will typically mate multiple times with other mates during the mating season. This is a major way to create genetic variation within the Red Milkweed Beetle populations.

  After eggs within the female T. tetrophthalmus have been fertilized by the sperm from one of her male mates, she will lay her eggs at the base of the stem of a milkweed plant, Asclepias syriaca (Reinhartz, 2014). The female may also choose to insert her larvae into a nearby stalk of grass. Approximately 10 to 15 eggs are deposited from a female when she inserts them into the milkweed plant (Matter, 2009). From the late summer months through the winter, the larvae will hatch and utilize the roots of the milkweed plant they were inserted into by their mother as a food source (Reinhartz, 2014). During the late months of spring, the previously larval T. tetrophthalmus dig through the soil to emerge as adult Red Milkweed Beetles. Throughout the summer months, the adult beetles mate, lay their eggs in the milkweed plants, and then die during the fall months to complete their lifecycle (Reinhartz, 2014).

 Continue to the next page, interactions, for more learning fun!