Identification and Control of the Angelica Swallowtail Caterpillar Pest

The angelica swallowtail, also known as the fennel swallowtail, belongs to the order Lepidoptera, family Papilionidae.

1. Damage situation: The larvae cause damage, feeding on leaves at night, creating notches, and in severe cases eating all the leaves so that only the petioles and veins remain; they also feed on flowers and fruits. This insect has a large appetite, seriously affecting the growth of angelica and reducing yield.

2. Morphological characteristics

Adult: A large butterfly, with spring and summer forms. The summer form has a body length of about 25 mm and a wingspan of 90 mm; the spring form is slightly smaller. The body is yellow, with black stripes running longitudinally along the back. Both forewings and hindwings are yellow, with the outer margins and veins black, forming a pattern of alternating yellow and black markings. The base of the forewing is black, scattered with yellow scales. The hindwing also has yellow and black markings, with 1 reddish-brown round spot at the posterior margin angle, surrounded by 6 blue spots of varying sizes.

Egg: Pale yellow, spherical.

Larva: Black when newly hatched, turning green after the 3rd instar, with a body length of 52-55 mm. The head has two black stripes, and each segment of the thorax and abdomen has short black transverse bands on the dorsal side.

Pupa: Yellow-green or pale yellowish-brown, elongated and slightly curved, with 2 horn-like protrusions on the head, and 1 small protrusion on the thorax dorsum and thorax sides.

3. Occurrence and damage pattern: 2-3 generations occur per year, overwintering as pupae attached to branches. They emerge in early to mid-April of the following year. The 1st generation larvae occur from May to June, and adults emerge from June to July. The 2nd generation adults occur from July to August. Adults are active during the day, laying eggs on angelica leaves. After the larvae hatch, they hide under the leaves during the day and feed on the leaves at night. Damage is more severe from May to June and from late July to August. After October, the larvae pupate and overwinter.

4. Control measures: (1) In the early stage of larval occurrence and before the 3rd instar, manually capture and kill the larvae in combination with field management. (2) During the occurrence period, spray with 90% trichlorfon at 1000 times dilution, once a week, for 2-3 consecutive sprays.