''Macrodactylus subspinosus'' is a

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n beetle of the family

Scarabaeidae The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...

. The members of this genus are known as "Rose chafers", not to be confused with the

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

an "Rose chafer", ''

Cetonia aurata ''Cetonia aurata'', called the rose chafer or the green rose chafer, is a beetle, long, that has a metallic structurally coloured green and a distinct V-shaped scutellum. The scutellum is the small V-shaped area between the wing cases; it may ...

''. ''M. subspinosus'' occurs from

Eastern Canada Eastern Canada (also the Eastern provinces or the East) is generally considered to be the region of Canada south of the Hudson Bay/Strait and east of Manitoba, consisting of the following provinces (from east to west): Newfoundland and Labrador, ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

and is considered a pest of many crops and flowers. It is given its common name of rose chafer because it eats the leaves of roses, although it also feeds on many other plants.

Description

The rose chafer has a yellowish-tan coloured body that is about in length, with wings that do not completely cover the abdomen. The beetle has six long, spiny, reddish-brown legs that gradually become darker towards the end of the appendage. It has two short lamellate antennae that end in a club of flat plates and it has chewing mouthparts. Rose chafers are covered in dull yellow hairs which give the body its characteristic colour, however with age and with normal activity the hairs are worn off the head and thorax revealing a black colour. It is thus possible to distinguish between older and younger beetles, as older beetles will have fewer hairs and thus be darker in colour. Females tend to lose more hairs, especially on the thorax due to the mating process, and can also appear darker in colour. Females also tend to be more robust than the male. The eggs of the rose chafer are about 1 mm in length and are oval, white and shiny. The larvae are white C-shaped grubs that when mature develop a brown head capsule and three distinct pairs of legs. The pupae are yellowish-brown in colour and are about 15 mm in length.

Natural history

Life cycle

As a member of the order

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

, the rose chafer undergoes

complete metamorphosis Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygo ...

during its development. In late May, white-bodied larvae, about long, pupate after having overwintered deep in the soil. Once they have emerged from their pupal case, adults live for 3–6 weeks, during which time they will feed on plant material and mate. Their eggs are laid in sandy soils, deep, and hatch in 1–3 weeks. This new generation of larvae will feed on the roots of grasses, weeds, and some ornamental garden plants during the rest of the summer, before they burrow deep in the soil to overwinter; these larvae will emerge as adults in the following year.

Behaviour

After adult rose chafers emerge in late May to mid-June, they aggregate on leaves, buds, flowers, and fruit, in order to feed and mate. By chewing on plant tissues, the rose chafer induces the release of volatile compounds from the plant. Using their antennae, rose chafers can detect the plant compounds in the air and orient themselves in the direction of the feeding conspecific, leading to an aggregation of the beetles. Male rose chafers also orient themselves preferentially toward virgin females as opposed to mated females, though it is unknown whether they are detecting

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s released by virgin females, or the release of plant volatiles induced by the feeding virgin females.

Damage

The adult beetle feeds on the foliage, flowers, and fruit of many plants including grapes, apples, peaches, chestnuts, roses, and other garden flowers and fruits. On roses it skeletonizes the leaves, which can be rather bothersome for avid gardeners. Rose chafers are also a problem for vineyards as they eat the grapes at bloom as well as skeletonize the leaves. They also tend to appear suddenly and in swarms, and vines with over 100 rose chafers per plant have been observed. This huge amount of damage can result in almost total loss of photosynthetically active leaf area as well as reducing or prohibiting pollination. The larvae also cause damage as they feed on the roots of the plants, which can limit growth.

Management

Small number of beetles (2-3 per plant) can be mechanically removed (hand picking, hand held vacuum). A number of insecticides are also effective for large scale infestations.Rose chafers

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

Extension, accessed 2018

References

External links

Rose ChafersRose Chafer images on "BugGuide.net"
{{Taxonbar, from=Q3274895 Melolonthinae Beetles of North America Agricultural pest insects Insect pests of ornamental plants Beetles described in 1775 Taxa named by Johan Christian Fabricius