Barb was dumping plant debris into the compost pile when she noticed this bug crawling around in it. Lifting up some of the old scraps revealed even more of them. They measured 3/8" (10 mm) and required magnification for final identification as small milkweed bugs, SMB - Lygaeus kalmii.
|Box elder Bug|
The distinctive coloration of SMB made the identification relatively easy. It has a bright orange incomplete "X" on the back and the upper black marking is somewhat heart shaped. The anterior edge of the pronotum (the plate covering the first portion of the thorax) has two small black spots. L. kalmii also has a small red spot on the back of the head extending forward, visible only with magnification.
When I think of milkweed, I associate it with the poster child of lepidoptera, the monarch butterfly. SMB feeds on milkweed seeds as well as the nectar from other forbs. They can also predate on small insects when other food sources are depleted.
The adults lay their eggs on milkweed in the spring and the larvae require milkweed to grow. They absorb and store the milkweeds toxin glycosides which are harmless to them but serve as a defense against predators. Actually at least four other insects feed on milkweed without ill effect from the toxic chemical.
|Large milkweed bugs - Wikimedia|
Our final contestant lacks aposematic coloration. The milkweed stem weevil, Rhyssomatus lineaticollis, can be quite destructive of rare and endangered milkweed species.
"Adults initially feed on the apical leaves and then, after feeding, female weevils walk to lower parts of the stem and chew several sequential holes in the stem, creating a continuous scar. Females lay a single egg per hole and larvae complete development inside the stem while feeding on pith tissue." bugguide.net
Milkweed stem weevil - Ken at Bugguides
|A mastication of caterpillars|
All insects that have milkweed in their diet at some part of their life cycle are poisonous to their predators because of the toxic cardiac glycosides contained in milkweed sap. Brightly colored or not, don't eat them!
Got Milk-weed seeds? MDC is collecting them for monarchs. Store them in a plastic bag and we will get them to MDC at a later time.