HPIPM:Hollyhock Weevil

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Compiled by Whitney Cranshaw, Colorado State University:

Colorado Insects of Interest

Hollyhock Weevil

Figure 1. Hollyhock weevils. The female, with the longer beak, is under the male on the right.

Scientific Name: Rhopalapion longirostre (Olivier)

Order: Coleoptera (Beetles)
Family: Brentidae (Straight-snouted weevils)

Identification and Descriptive Features: Hollyhock weevils are small, gray snout beetles with orange legs. Their most notably feature is their forward projecting snout that is extremely long, particularly on the female. They are common insects found on hollyhock leaves and flower buds throughout much of summer.

Distribution in Colorado: The hollyhock weevil is a native to Europe but now can likely occur throughout the state wherever hollyhock is grown. Distribution of the insect undoubtably has been largely affected by human movement of the insect by transporting infested hollyhock seed so incidence of the insect can be patchy.

Figure 2. Hollyhock weevils on a hollyhock bud. The female on the lower left has chewed into the bud, burying her snout.

Life History and Habits: Hollyhock weevils usually spend the winter in the adult stage in the vicinity of previously infested hollyhock plantings; some developing late in the season may winter within seed pods, emerging as adults the following season. In spring the adults move to growing hollyhock plants where they chew buds, tender stems and emerging leaves. As the leaves unravel and emerge they have a “shotholed” appearance of numerous small holes produced by the earlier feeding.

As flower buds begin to form, much of the activity shifts to this area of the plant. Mating can very frequently be observed, with the smaller male perched on the back of the female. (Males will also remain with the female to deter other males from mating.) The female uses her very long snout to chew deeply into the developing seed and lays an egg in the cavity. The cream-colored grub then consumes the seed and pupates when feeding is completed.

Management of Hollyhock Weevil in Gardens: Like many weevils, hollyhock weevils will usually drop when disturbed by shaking the plant. They can then be collected and destroyed. Regular removal and disposal of seed pods will destroy developing larvae. Many garden insecticides likely will be effective for controlling adult weevils exposed on plants.

Figure 3. Small holes in hollyhock leaves from feeding injuries produced by the hollyhock weevil.

Figure 4. Hollyhock seed pod infested with hollyhock weevil larvae. The circular plugs are produced on seeds that harbor a developing insect.

Figure 5. Hollyhock weevil larva exposed from hollyhock seed.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.