Cicada killer wasps emerging in Central Texas

Over the past week I've been getting questions on large wasps that people are seeing emerging from the ground.  They want to know what they are and be reassured that they are not the Asian giant hornet.  These wasps are known as cicada killers and are aptly named.  Cicada killers are large wasps, reaching around 1.5 inches.  They have a rusty colored head and thorax with a black and yellow patterned abdomen.  The wings are also rusty in color, but transparent.

Cicada killer wasps are solitary, but multiple wasps may be seen in the same area at times.  Males are known for aggressively defending their territory and patrolling burrows created underground. While males dive bomb someone who walks into their territory, they are incapable of stinging.  Female cicada killers are capable of stinging, but generally reserve their stinger for paralyzing prey and tend to only sting in defense.

Adult wasps feed on nectar and tree sap while immatures feed on cicadas.  Adult female wasps locate a cicada, sting it causing the cicada to become paralyzed and then carry it back to the tunnel created in the ground.  She drags the cicada into the tunnel and to a nesting chamber.  Each chamber is provisioned with 1-2 cicadas before the female lays an egg on the leg of the cicada and seals up the chamber.  Once the egg hatches, the wasp larva eats the provided cicadas, overwintering in the ground as a mature larva, and pupating the following year to emerge again when cicadas are available.

Tunnels are about a foot deep and about 2 feet long with 3-4 chambers off to the sides for provision cicadas for larvae.

These wasps are considered to be beneficial, so no control is recommended.  If you feel that you need to manage them, you can:
1. Use clear plastic tarp over the tunnel area to solarize
2. Sprinkle and insecticidal dust around the tunnel opening and tamp it down with your foot

Summer is here....and so are cicadas!

Have you been hearing loud noises in trees when you go outside lately? Male cicadas are well known for their "song".  They rest on trees and produce a whining sound that is attractive to females (cicada females, that is...). The sound is produced by two vibrating membranes on the side of the cicada abdomen.  Fortunately, for those who do not enjoy the "music", female cicadas do not "sing".

Cicadas are fairly large insects with some growing over 1 1/2 inches. Color can vary depending upon the species, but many are browns and greens.  All cicadas have bulging eyes and, on adults, wings that are held roof-like over the body.  The wings are semi-transparent with thick veins.

Cicadas have a 2-5 year life cycle, the majority of which is spent underground.  After mating, females insert egg clusters into branches of trees using their saw-like ovipositor (egg laying structure).  Eggs hatch after about 6 weeks and small nymphs drop to the ground where they burrow into the soil. Nymphs feed on the sap of tree roots with their piercing-sucking mouthparts.  After nymphs have fully developed, they emerge from the ground at night and climb up nearby objects like tree trunks, plants, fences, etc.  Adult cicadas emerge from the last nymphal stage, leaving behind the exuviae (cast skin/ exoskeleton).  Adults can live 5-6 weeks.

Cicada killers

Cicada exoskeleton.

Have you seen any cicada exoskeletons (they look like Garthim from Jim Henson's The Dark Crystal) lately? I found one near my front porch last week.  This time of year, with the cicadas (and their noise) come the topic of today's post- cicada killers.  These large wasps can be startling to see when they fly around trees or low over the lawn.  They reach about 1.5 inches in length with dusky wings, reddish-brown thorax and a yellow and black abdomen.

Cicada killer wasp.

Females are pretty docile, but males are territorial and will fly at you until you leave their area.  Only female wasps (and bees) can sting as the stinger is a modified egg-laying structure.  The female cicada killers create burrows in the ground and then go off to sting cicadas.  The cicadas are paralyzed by the sting and taken by the wasp back to the burrow where she digs a side tunnel, crams in the cicada and lays an egg on it.  When the egg hatches, it will feed on the cicada provided.

That being said, cicada killers can be considered beneficial as they help to cut down on the cicada population.  They can also be considered a pest since sometimes people will have holes all over the yard from the wasps' tunneling behavior.  If you fall into the latter category and want to do something to manage the population, you can sprinkle a insecticidal dust over the holes and tamp it down with your shoe.