Explanation of Names
cristatus (L) 'crested'
The common name derives from the cog-like projection on the back of the adult
at 28-36 mm (females larger than males), our largest assassin bug(1)
The "wheel" on the adult insect's back is unmistakable. Nymphs are mostly red.
mostly: e. US to CO-NM - Map (2)
, (ON-FL to NE-CA) to C. America (Hagerty & McPherson 2000)
Found where prey is abundant: adults often lurk on composite flowers attractive to insects, or prowl in trees where caterpillars are plentiful
Nymphs hatch in spring, adults are found late spring into fall and early winter
All stages prey upon other insects (caterpillars, aphids, bees, sawflies, etc.) and are considered beneficial
One generation per year. Adults mate in fall, the male then guards the female
since other males may try to move in
Clusters of eggs (described as "brown bottles with fancy stoppers") are laid in hexagonal clusters of 42-182 on trees, shrubs or other structures, generally within 4 feet of the ground
Here's a great series from Jim Kramer on eggs and hatching (more in the guide):
After eggs hatch in spring
, nymphs develop slowly. They must
watch out for predators including their own brethren!
(about 3 months to maturity): red/black
They hunt down their prey such as this one walking on a Hyphantria tent
They have a heavy beak for feeding
pierce their prey and eat
They need to molt in order to grow, described by one contributor as looking like an orange bug with a spider stuck on its tail!
Which can be fatal if they can't extricate themselves:
and leave behind just an empty shell, inverted tracheal tubes and all
Adults are generally not seen until May even in warmest parts of US
Some are unfortunate victims of parasitoids
Despite chemical defenses
Others thrive, sometimes even with deformed wheels
reproduce, and the cycle begins again. Adults may survive into December in warmest regions.
CAUTION: The bug can inflict a very painful bite. Ammonia water and magnesium sulphate soaks can be helpful in relieving pain from the bite. Perhaps (like fire ant bites), quick treatment with an ammonia-based household cleaner may be effective if you have been bitten. More suggestions here
Hagerty A.M., McPherson J.E. (2000) Life history and laboratory rearing of Arilus cristatus
(Heteroptera: Reduviidae) in Southern Illinois. The Florida Entomologist 83(1): 58-63. (Full text
Todd J.N. (1937) Life history of the wheel-bug, Arilus cristatus (Linn.) (Hemiptera: Reduviidae). Ent. News 48: 226-228.