PestLow Severity

California Tent Caterpillar

Malacosoma californica

A moth whose larvae construct characteristic silk tents around twig tips and feed on terminal leaves for about 6 weeks. While they can cause heavy defoliation, the resulting damage is usually of little importance since trees recover readily, especially if fertilized.

Peak Season: Overwintering: As eggs encircling twigsEgg hatch: Early spring as leaves unfoldActive feeding: Spring for about 6 weeksPupation: Mid-summer, lasting one monthAdult emergence: Late August to SeptemberAdult activity: Cluster around lights at night
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California tent caterpillar larvae and tent

Identification & Symptoms

What to Look For

Webbing of branch terminals with silk tents
Chewing and defoliation of terminal leaves
Silk tents enlarging as larvae grow
Heavy defoliation sometimes occurs
Orange-brown caterpillars with blue dots and reddish-brown hairs visible

Potential Damage

Terminal leaf defoliation
Webbing damage to branch tips
Aesthetic damage from silk tents
Generally minor damage as trees recover readily
Heavy defoliation possible but trees typically bounce back with fertilization

Lifecycle

Single generation per year. Eggs overwinter encircling twigs, hatch in early spring as new leaves unfold. Larvae construct growing tents and feed through 6 instars. Pupation in mid-summer lasting about one month. Adults emerge and lay eggs in late August/September.

Professional Treatment Approach

1

Imisol treatments in early spring targeting newly hatched larvae

2

Mechanical removal of egg masses during winter dormancy

3

Imicide applications when larvae are young and most vulnerable

4

Fertilization programs to help trees recover from defoliation

5

Time treatments when larvae first emerge from eggs

Recommended Mauget Products

Imisol

Professional-grade treatment specifically effective against california tent caterpillar.

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Imicide

Professional-grade treatment specifically effective against california tent caterpillar.

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