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Abstract Parents can provide care to their offspring to increase their offspring's chance of survival. There are various types of parental care across insect taxa, one of which is maternal investment. Lipids, the most energy‐dense of macronutrients, are considered a good estimate of maternal investment in insects. However, it is not clear how different environments, such as host plants, can impact provisioning, especially for dietary generalists that feed on an array of plant species with varying quality. Using an extreme dietary generalist, fall webworm (FW,Hyphantria cunea), we investigated if females provision different amounts of lipids into their eggs depending on the diet they fed upon as larvae. We measured the lipid content of FW egg clusters from parents reared on seven host plant species of varying quality. We found that parental host plants influenced egg provisioning, such that provisioning depends on host plant but also increases most for parents reared on low‐quality diets. Additionally, we found that female parents with heavier pupal mass produced egg clusters with greater lipids per egg. Our results provide evidence that egg provisioning can depend on the parental environment and suggest that the use of low‐quality host plants by generalist herbivores may be partially overcome via maternal investment. 

Abstract For herbivorous insects with a broad diet breadth, host plant identity can influence larval development by either accelerating or delaying growth. For some species of Lepidoptera, the number of larval instars varies depending on the host plant’s identity. Fall webworm (Hyphantria cunea, Drury) is a polyphagous herbivore that feeds on over 450 host plants worldwide. Of the 2 morphotypes (red- and black-head) of fall webworm, the number of instars for the red-head fall webworms has not been characterized. Given its broad diet breadth, fall webworm developmental stages may vary with plant identity. We investigated whether host plant identity affected the number of instars observed during red-head fall webworm development. We measured the head capsules of over 6,000 fall webworm larvae reared on 6 different plants commonly eaten by fall webworms in Colorado. We modeled head capsule widths as Gaussian mixture models, with a Gaussian distribution that corresponded to each instar. We show that our red-head fall webworms varied in number of instars depending on the identity of their host plant upon which they fed. We found that red-head fall webworm exhibited 7 instars on 5 of the host plants and 8 instars on 1 host plant that we studied. Our results for the number of instars for red-head fall webworm are consistent with reports of the number of instars for black-head fall webworm. Our research provides insight into the influence of host plant identity on fall webworm development, which can be used to advance lab and field research of this species.