Aphids and their predators on marsh elder – June 23, 2014

Marsh elder aphids support one of the more diverse and easily observable salt marsh insect communities. Aphids on the marsh have no protection against predators or parasitoids. They are absolutely vulnerable. The only counter-measure available to them is high reproductive rate (by giving live births!) and overpowering by sheer numbers.

Female aphids giving birth to little nymphs

 One of the most conspicuous predators are the ladybugs, larvae and adults. They are strikingly beautiful animals. When it catches an aphid, the ladybug larva tears it apart with the powerful mandibles or jaws.

There are also some unusual creatures feeding on aphids. This is a flower fly larva (family Syrphidae). The larva looks like a greenish maggot. It actively searches for the aphid prey and when captured with a dart like mandibles, the larva sucks them dry. 

Aphids are practically sitting ducks for parasitoids, mostly tiny braconid wasps.  11 out of 33 or about 30% of the aphids on this leaf are mummies containing braconid wasp larvae. Aphid mummies look like dark inflated globules as opposed to the more normal reddish egg shape.