Macrodactylus subspinosus
(Fabricius, 1775)
American Rose Chafer, Rose Chafer
Macrodactylus subspinosus, commonly known as the , is a to North America. It is a significant agricultural and horticultural pest that feeds on the foliage, flowers, and fruit of numerous plants, including roses, , apples, and peaches. emerge in late May to mid-June, live 3–6 weeks, and aggregate on plants using volatiles to locate feeding sites. The undergoes with deep in soil and feeding on plant roots.
Pronunciation
How to pronounce Macrodactylus subspinosus: //ˌmækroʊˈdæktɪləs sʌbˈspaɪnoʊsəs//
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Distinguished from the European (Cetonia aurata) by its Nearctic distribution and smaller size. Separated from other Macrodactylus by the combination of exposing the , yellowish-tan hairy body, and six long spiny legs. resemble other but occur in sandy soils feeding on grass and weed roots. can be aged by degree of hair wear: younger retain more hairs, older beetles show black on and .
Images
Appearance
have a yellowish-tan body covered in dull hairs, measuring 8–13 mm in length. The are , leaving part of the exposed. Six long, spiny legs are reddish- and darken distally. are short, , and clubbed with flat plates. are present. With age, hairs wear off the and , revealing black underlying ; females often appear darker due to greater hair loss during mating. Females are more than males. are oval, , shiny, and approximately 1 mm. are white, C-shaped with a brown head capsule and three pairs of legs. are yellowish-brown and about 15 mm long.
Habitat
Found in sandy soils where females oviposit 15 cm deep. Larval includes soil among grass roots, weeds, and ornamental garden plants. habitat spans agricultural fields, vineyards, orchards, and gardens where plants occur. Sandy substrate is critical for and larval development.
Distribution
to the Nearctic region. Range extends from Eastern Canada (Ontario, Quebec) west to Colorado and south to Texas. Additional records from Montana, Nebraska, North and South Carolina, South Dakota, Wisconsin, Iowa, Indiana, Maryland, and Massachusetts. Also reported from Neotropical regions including Rica, Jamaica, and Nicaragua, though these may represent introductions or misidentifications.
Seasonality
emerge from late May to mid-June following of overwintered . Adult lifespan is 3–6 weeks. hatch in 1–3 weeks. Larvae feed through summer, then burrow deep into soil to overwinter. One per year.
Diet
feed on foliage, flowers, and fruit of diverse plants including roses, , apples, peaches, chestnuts, and other garden flowers and fruits. On roses, adults leaves. feed on roots of grasses, weeds, and ornamental garden plants.
Host Associations
- Rosa - foliage and flower Skeletonizes leaves; namesake
- Vitis - foliage, flower, and fruit Damages at bloom; problematic for vineyards
- Malus - foliage and fruit Apple feeding observed
- Prunus persica - foliage and fruit Peach feeding observed
- Castanea - foliage and fruit Chestnut feeding observed
- Poaceae - root Larval ; grass roots
- various weeds - root Larval
- ornamental garden plants - root and foliage Both and
Life Cycle
with one annually. Overwintered pupate in late May at approximately 18 mm length. emerge, feed, and mate for 3–6 weeks. laid in sandy soil at 15 cm depth hatch in 1–3 weeks. Larvae feed on roots through summer, then burrow deep to overwinter. occurs the following spring.
Behavior
aggregate on plants using volatile chemical cues. Feeding damage releases volatiles that attract additional via olfactory orientation. Males preferentially orient toward virgin females, though the specific mechanism (female vs. plant volatiles induced by virgin female feeding) remains unresolved. Adults are and active flyers. Swarming observed, with exceeding 100 individuals per vine reported in vineyards.
Ecological Role
that can reach causing significant and fruit damage. Larval root feeding may limit growth. mediated by plant volatiles creates localized high-density feeding . Role in through soil burrowing and root likely but unquantified.
Human Relevance
Major pest of agricultural and ornamental plants. documented in vineyards, orchards, and rose gardens. of leaves reduces photosynthetic capacity; flower and fruit feeding reduces yield. Larval root feeding stunts growth. Management includes hand-picking for small and for large- . Not legally protected; subject to control measures.
Similar Taxa
- Cetonia aurataAlso called '' but European; distinguished by complete covering , metallic green- coloration, and Palearctic distribution
- Macrodactylus angustatusCongeneric ; may overlap in range; specific distinguishing features require examination of and detailed morphological comparison
- Phyllophaga spp./; similar larval form and ; distinguished by larger size, different adult activity period, and complete
- Osmoderma scabraHermit ; similar C-shaped in soil; distinguished by larger size, different (decaying wood), and
Misconceptions
'' causes confusion with the unrelated European Cetonia aurata, which belongs to a different () and has different biology, appearance, and distribution.
More Details
Aggregation Pheromone System
The uses a unique system where feeding damage releases volatiles that attract . This differs from typical systems and represents plant- interaction-mediated aggregation.
Aging Technique
Degree of hair wear on and provides a reliable field method for distinguishing older from younger , with females typically showing more wear due to mating activity.
Soil Preference
Sandy soils are specifically selected for , potentially limiting distribution in heavy clay or compacted soils.